Add a workaround for a GCC bug that generates spurious warnings for PSTR()

git-svn-id: https://arducopter.googlecode.com/svn/trunk@900 f9c3cf11-9bcb-44bc-f272-b75c42450872

libraries/AP_Common/menu.cpp

@@ -12,6 +12,10 @@
 
 #include "include/menu.h"
 
+// Workaround for http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34734 
+#undef PSTR
+#define PSTR(s) (__extension__({static prog_char __c[] = (s); &__c[0];}))
+
 // statics
 char Menu::_inbuf[MENU_COMMANDLINE_MAX];
 Menu::arg Menu::_argv[MENU_ARGS_MAX + 1];