cmake-mode.el: Fix function name font-lock

Allow space separating name and opening parenthesis.

Auxiliary/cmake-mode.el

@@ -198,7 +198,7 @@ the indentation.  Otherwise it retains the same position on the line"
                               ,@(mapcar #'downcase cmake-keywords))
                           symbol-end))
      . font-lock-keyword-face)
-    (,(rx symbol-start (group (+ (or word (syntax symbol)))) ?\()
+    (,(rx symbol-start (group (+ (or word (syntax symbol)))) (* blank) ?\()
      1 font-lock-function-name-face)
     ("\\${?\\([[:alpha:]_][[:alnum:]_]*\\|[0-9]+\\|[$*_]\\)"
      1 font-lock-variable-name-face t)