Add explicit check against zero when looking to remove an option so that test doesn't treat the return value of grep as "true" always.

Bug 111653 r=bryner


git-svn-id: svn://10.0.0.236/trunk@108924 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/configure.in

@@ -2815,7 +2815,7 @@ MOZ_ARG_ENABLE_STRING(extensions,
         MOZ_EXTENSIONS=""
     elif test "$option" = "default"; then
         MOZ_EXTENSIONS="$MOZ_EXTENSIONS $MOZ_EXTENSIONS_DEFAULT"
-    elif test `echo "$option" | grep -c ^-`; then
+    elif test `echo "$option" | grep -c ^-` != 0; then
         option=`echo $option | sed 's/^-//'`
         MOZ_EXTENSIONS=`echo "$MOZ_EXTENSIONS" | sed "s/ ${option}//"`
     else