gdb: prefer m4 over gm4

fails on macos when using gm4.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

Author: nashif

configure

@@ -11686,7 +11686,7 @@ case " $build_configdirs " in
   *" bison "*) BISON='$$r/$(BUILD_SUBDIR)/bison/tests/bison' ;;
 esac
 
-for ac_prog in gm4 gnum4 m4
+for ac_prog in gnum4 m4 gm4
 do
   # Extract the first word of "$ac_prog", so it can be a program name with args.
 set dummy $ac_prog; ac_word=$2