Avoid GDB 7.5 warnings about "set main" in src/.gdbinit.

 src/.gdbinit: Use "set $dummy = ..." to avoid warnings from GDB 7.5
 and later about non-assignments with no effect.  See discussion at
 http://sourceware.org/ml/gdb-patches/2012-08/msg00518.html for
 details.

src/.gdbinit

@@ -18,9 +18,9 @@
 # Boston, MA 02110-1301, USA.
 
 # Force loading of symbols, enough to give us VALBITS etc.
-set main
+set $dummy = main + 8
 # With some compilers, we need this to give us struct Lisp_Symbol etc.:
-set Fmake_symbol
+set $dummy = Fmake_symbol + 8
 
 # Find lwlib source files too.
 dir ../lwlib

src/ChangeLog

+2012-08-20  Eli Zaretskii  <eliz@gnu.org>
+
+	* .gdbinit: Use "set $dummy = ..." to avoid warnings from GDB 7.5
+	and later about non-assignments with no effect.  See discussion at
+	http://sourceware.org/ml/gdb-patches/2012-08/msg00518.html for
+	details.
+
 2012-08-20  Dmitry Antipov  <dmantipov@yandex.ru>
 	Inline setter functions for Lisp_Objects slots of struct specbinding.