Autotools: Fix config.status script syntax

The init-cmds argument is appended to the config.status script with cat
command and variables $var are replaced during the cat step to their
values, so quoting these values fixes the syntax errors.

Fixes report in phpGH-14872

Author: petk

sapi/apache2handler/config.m4

@@ -124,5 +124,5 @@ AC_CONFIG_COMMANDS([apache2handler], [AS_VAR_IF([enable_zts], [yes],,
 | PHP with --enable-zts                                              |
 +--------------------------------------------------------------------+
   ])])])],
-  [APACHE_THREADED_MPM=$APACHE_THREADED_MPM; enable_zts=$enable_zts])
+  [APACHE_THREADED_MPM="$APACHE_THREADED_MPM"; enable_zts="$enable_zts"])
 fi