undef reg in gdb_curses.h

I tried to build gdb on the AIX machine in the GCC compile farm
(gcc111), but it failed in a couple of spots because gdb uses "reg" as
a variable name and the AIX <curses.h> defines "reg" to "register".

I saw that we already had a workaround for this lurking in utils.c, so
I just moved that to gdb_curses.h.

This fixed the problem on AIX and still builds on x86-64 Fedora 18.

2013-10-29  Tom Tromey  <tromey@redhat.com>

	* utils.c (reg): Move undefinition...
	* gdb_curses.h: ... here.  Update comment to mention AIX.

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2013-10-29  Tom Tromey  <tromey@redhat.com>
+
+	* utils.c (reg): Move undefinition...
+	* gdb_curses.h: ... here.  Update comment to mention AIX.
+
 2013-10-29  Nicolas Blanc  <nicolas.blanc@intel.com>
 
 	* exec.h (add_target_sections_of_objfile): New declaration.

gdb/gdb_curses.h

@@ -54,4 +54,12 @@
 extern int tgetnum (const char *);
 #endif
 
+/* SunOS's curses.h has a '#define reg register' in it.  Thank you Sun.  */
+/* Ditto for:
+   -bash-4.2$ uname -a
+   AIX power-aix 1 7 00F84C0C4C00  */
+#ifdef reg
+#undef reg
+#endif
+
 #endif /* gdb_curses.h */

gdb/utils.c

@@ -40,11 +40,6 @@
 #include <pc.h>
 #endif
 
-/* SunOS's curses.h has a '#define reg register' in it.  Thank you Sun.  */
-#ifdef reg
-#undef reg
-#endif
-
 #include <signal.h>
 #include "timeval-utils.h"
 #include "gdbcmd.h"