Make symfile_add_flags and objfile->flags strongly typed

This makes these flag types be "enum flag" types.  The benefit is
making use of C++'s stronger typing -- mixing the flags types by
mistake errors at compile time.

This caught one old bug in symbol_file_add_main_1 already, fixed by
this patch as well:

  @@ -1318,7 +1326,7 @@ symbol_file_add_main_1 (const char *args, int from_tty, int flags)
	what is frameless.  */
     reinit_frame_cache ();

  -  if ((flags & SYMFILE_NO_READ) == 0)
  +  if ((add_flags & SYMFILE_NO_READ) == 0)
       set_initial_language ();
   }

Above, "flags" are objfile flags, not symfile_add_flags.  So that was
actually checking for "flag & OBJF_PSYMTABS_READ", which has the same
value as SYMFILE_NO_READ...

I moved the flags definitions to separate files to break circular
dependencies.

Built with --enable-targets=all and tested on x86-64 Fedora 23.

gdb/ChangeLog:
2016-10-26  Pedro Alves  <palves@redhat.com>

	* coffread.c (coff_symfile_read): Use symfile_add_flags.
	* dbxread.c (dbx_symfile_read): Ditto.
	* elfread.c (elf_symfile_read): Ditto.
	* inferior.h: Include symfile-add-flags.h.
	(struct inferior) <symfile_flags>: Now symfile_add_flags.
	* machoread.c (macho_add_oso_symfile, macho_symfile_read_all_oso)
	(macho_symfile_read, mipscoff_symfile_read): Use
	symfile_add_flags.
	* objfile-flags.h: New file.
	* objfiles.c (allocate_objfile): Use objfile_flags.
	* objfiles.h: Include objfile-flags.h.
	(struct objfile) <flags>: Now an objfile_flags.
	(OBJF_REORDERED, OBJF_SHARED, OBJF_READNOW, OBJF_USERLOADED)
	(OBJF_PSYMTABS_READ, OBJF_MAINLINE, OBJF_NOT_FILENAME): Delete.
	Converted to an enum-flags in objfile-flags.h.
	(allocate_objfile): Use objfile_flags.
	* python/py-objfile.c (objfpy_add_separate_debug_file): Remove
	unnecessary local.
	* solib.c (solib_read_symbols, solib_add)
	(reload_shared_libraries_1): Use symfile_add_flags.
	* solib.h: Include "symfile-add-flags.h".
	(solib_read_symbols): Use symfile_add_flags.
	* symfile-add-flags.h: New file.
	* symfile-debug.c (debug_sym_read): Use symfile_add_flags.
	* symfile-mem.c (symbol_file_add_from_memory): Use
	symfile_add_flags.
	* symfile.c (read_symbols, syms_from_objfile_1)
	(syms_from_objfile, finish_new_objfile): Use symfile_add_flags.
	(symbol_file_add_with_addrs): Use symfile_add_flags and
	objfile_flags.
	(symbol_file_add_separate): Use symfile_add_flags.
	(symbol_file_add_from_bfd, symbol_file_add): Use symfile_add_flags
	and objfile_flags.
	(symbol_file_add_main_1): : Use objfile_flags.  Fix add_flags vs
	flags confusion.
	(symbol_file_command): Use objfile_flags.
	(add_symbol_file_command): Use symfile_add_flags and
	objfile_flags.
	(clear_symtab_users): Use symfile_add_flags.
	* symfile.h: Include "symfile-add-flags.h" and "objfile-flags.h".
	(struct sym_fns) <sym_read>: Use symfile_add_flags.
	(clear_symtab_users): Use symfile_add_flags.
	(enum symfile_add_flags): Delete, moved to symfile-add-flags.h and
	converted to enum-flags.
	(symbol_file_add, symbol_file_add_from_bfd)
	(symbol_file_add_separate): Use symfile_add_flags.
	* xcoffread.c (xcoff_initial_scan): Use symfile_add_flags.

gdb/objfile-flags.h

@@ -0,0 +1,71 @@
+/* Definition of objfile flags.
+
+   Copyright (C) 1992-2016 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#if !defined (OBJFILE_FLAGS_H)
+#define OBJFILE_FLAGS_H
+
+#include "common/enum-flags.h"
+
+/* Defines for the objfile flags field.  Defined in a separate file to
+   break circular header dependencies.  */
+
+enum objfile_flag
+  {
+    /* When an object file has its functions reordered (currently
+       Irix-5.2 shared libraries exhibit this behaviour), we will need
+       an expensive algorithm to locate a partial symtab or symtab via
+       an address.  To avoid this penalty for normal object files, we
+       use this flag, whose setting is determined upon symbol table
+       read in.  */
+    OBJF_REORDERED = 1 << 0,	/* Functions are reordered */
+
+    /* Distinguish between an objfile for a shared library and a
+       "vanilla" objfile.  This may come from a target's
+       implementation of the solib interface, from add-symbol-file, or
+       any other mechanism that loads dynamic objects.  */
+    OBJF_SHARED = 1 << 1,	/* From a shared library */
+
+    /* User requested that this objfile be read in it's entirety.  */
+    OBJF_READNOW = 1 << 2,	/* Immediate full read */
+
+    /* This objfile was created because the user explicitly caused it
+       (e.g., used the add-symbol-file command).  This bit offers a
+       way for run_command to remove old objfile entries which are no
+       longer valid (i.e., are associated with an old inferior), but
+       to preserve ones that the user explicitly loaded via the
+       add-symbol-file command.  */
+    OBJF_USERLOADED = 1 << 3,	/* User loaded */
+
+    /* Set if we have tried to read partial symtabs for this objfile.
+       This is used to allow lazy reading of partial symtabs.  */
+    OBJF_PSYMTABS_READ = 1 << 4,
+
+    /* Set if this is the main symbol file (as opposed to symbol file
+       for dynamically loaded code).  */
+    OBJF_MAINLINE = 1 << 5,
+
+    /* ORIGINAL_NAME and OBFD->FILENAME correspond to text description
+       unrelated to filesystem names.  It can be for example
+       "<image in memory>".  */
+    OBJF_NOT_FILENAME = 1 << 6,
+  };
+
+DEF_ENUM_FLAGS_TYPE (enum objfile_flag, objfile_flags);
+
+#endif /* !defined (OBJFILE_FLAGS_H) */