Changes to support GDB running on DOS using GO32 and H8 support

* defs.h: if xm.h doesn't define FOPEN_RB, include "fopen-same.h",
	allowing hosts with different text and binary file formats to
	work.
	* coffread.c (read_coff_symtab): changed calling convention and
	operation - now it opens its own file with FOPEN_RB rather than
	duping and fdopening the provided handle.
	* dbxread.c, cplus-dem.c: #include mangling.
	* exec.c: If O_BINARY isn't defined, set it to 0, call openp for
	binary files oring in the right bit.
	* utils.c, terminal.h, inflow.c: hackery because dos doesn't have terminals.
	* remote-hms.c: cleanup to use the new remote serial stuff
	* serial.h, ser-termios.c, ser-go32.c: newfiles to provide host
	independent remote terminal I/O.
	* remote.c: if DONT_USE_REMOTE is defined, then don't use it.
	* source.c (openp): fix off by one problem removing / - can now
	open a source file in the root directory with DOS.
	* values.c (value_as_pointer): remove bogus address bits from
	long. (unpack_long): unpack into unsigned long/short if pointer.

gdb/.Sanitize

@@ -90,6 +90,7 @@ gdbcmd.h
 gdbcore.h
 gdbtypes.c
 gdbtypes.h
+go32-xdep.c
 gould-pinsn.c
 gould-xdep.c
 h8300-tdep.c
@@ -171,6 +172,9 @@ sparc-xdep.c
 stack.c
 standalone.c
 stuff.c
+serial.h
+ser-termios.c
+ser-go32.c
 sun3-xdep.c
 sun386-xdep.c
 symfile.c
@@ -246,7 +250,6 @@ xcoffread.c
 xcoffsolib.c
 xcoffsolib.h
 xm-3b1.h
-xm-m88k.h
 xm-altos.h
 xm-amix.h
 xm-apollo68v.h
@@ -254,6 +257,7 @@ xm-arm.h
 xm-bigmips.h
 xm-convex.h
 xm-delta88.h
+xm-go32.h
 xm-hp300bsd.h
 xm-hp300hpux.h
 xm-i386mach.h
@@ -265,6 +269,7 @@ xm-irix3.h
 xm-irix4.h
 xm-isi.h
 xm-m68k.h
+xm-m88k.h
 xm-merlin.h
 xm-mips.h
 xm-news.h