build-sys: fix gtkdocize check

gtkdocize: GTK_DOC_CHECK not called in configure.ac

Fixup for 6581f00f7e.

configure.ac

@@ -72,8 +72,8 @@ AC_PATH_PROG([SETCAP], [setcap], [/usr/sbin/setcap])
 AC_PATH_PROG([KILL], [kill], [/usr/bin/kill])
 
 # gtkdocize greps for '^GTK_DOC_CHECK', so it needs to be on its own line
-m4_ifdef([GTK_DOC_CHECK],
-         [GTK_DOC_CHECK([1.18],[--flavour no-tmpl])],
+m4_ifdef([GTK_DOC_CHECK], [
+GTK_DOC_CHECK([1.18],[--flavour no-tmpl])],
          [AM_CONDITIONAL([ENABLE_GTK_DOC], [false])
           enable_gtk_doc=no])