Remove duplicated #include's from GDB

This patch simply removes duplicated #include statements in the gdb/
directory.  If there are two duplicated #include statements, this patch
keeps the first #include and removes the second.

Those duplicates have been found by using the checkincludes.pl tool from
the Linux kernel and double checked manually once again if the #include
statements are affected by #ifdef macros.

2014-01-06  Honggyu Kim  <hong.gyu.kim@lge.com>

	* ada-lang.c: Remove duplicated include statements.
	* alphabsd-nat.c: Ditto.
	* amd64-darwin-tdep.c: Ditto.
	* amd64fbsd-nat.c: Ditto.
	* auto-load.c: Ditto.
	* ax-gdb.c: Ditto.
	* breakpoint.c: Ditto.
	* dbxread.c: Ditto.
	* fork-child.c: Ditto.
	* gdb_usleep.c: Ditto.
	* i386-darwin-tdep.c: Ditto.
	* i386fbsd-nat.c: Ditto.
	* infcmd.c: Ditto.
	* inferior.c: Ditto.
	* jv-lang.c: Ditto.
	* linux-nat.c: Ditto.
	* linux-tdep.c: Ditto.
	* m68kbsd-nat.c: Ditto.
	* m68klinux-nat.c: Ditto.
	* microblaze-tdep.c: Ditto.
	* mips-linux-tdep.c: Ditto.
	* mn10300-tdep.c: Ditto.
	* nto-tdep.c: Ditto.
	* opencl-lang.c: Ditto.
	* osdata.c: Ditto.
	* printcmd.c: Ditto.
	* regcache.c: Ditto.
	* remote-m32r-sdi.c: Ditto.
	* remote.c: Ditto.
	* symfile.c: Ditto.
	* symtab.c: Ditto.
	* tilegx-linux-nat.c: Ditto.
	* tilegx-tdep.c: Ditto.
	* tracepoint.c: Ditto.
	* valops.c: Ditto.
	* vaxbsd-nat.c: Ditto.
	* windows-nat.c: Ditto.
	* xtensa-tdep.c: Ditto.

gdb/windows-nat.c

@@ -43,7 +43,6 @@
 #include <sys/cygwin.h>
 #include <cygwin/version.h>
 #endif
-#include <signal.h>
 
 #include "buildsym.h"
 #include "filenames.h"