Change the definition of --enable-optimize to be less ambiguous.

configure

@@ -108,7 +108,7 @@ ac_help="$ac_help
   --enable-crash-on-assert
                           Make NS_ASSERTION crash on Unix"
 ac_help="$ac_help
-  --enable-optimize(=val) Enable code optimizations level (val) "
+  --enable-optimize(=flag) Enable code optimizations (flag, ie. -O2) "
 ac_help="$ac_help
   --disable-debug         Disable building with debug info"
 ac_help="$ac_help

configure.in

@@ -3091,7 +3091,7 @@ then
 fi
 
 MOZ_ARG_ENABLE_STRING(optimize,
-[  --enable-optimize(=val) Enable code optimizations level (val) ],
+[  --enable-optimize(=flag) Enable code optimizations (flag, ie. -O2) ],
     [ if test "$enableval" != "no"; then
 	MOZ_OPTIMIZE=1
 	if test -n "$enableval" && test "$enableval" != "yes"; then