Add php files for make dist.
diff --git a/configure.ac b/configure.ac
index a454bbe..896f347 100644
--- a/configure.ac
+++ b/configure.ac
@@ -31,7 +31,7 @@
AC_ARG_VAR(DIST_LANG, [language to include in the distribution package (i.e., make dist)])
case "$DIST_LANG" in
"") DIST_LANG=all ;;
- all | cpp | csharp | java | python | javanano | objectivec | ruby | js) ;;
+ all | cpp | csharp | java | python | javanano | objectivec | ruby | js | php) ;;
*) AC_MSG_FAILURE([unknown language: $DIST_LANG]) ;;
esac
AC_SUBST(DIST_LANG)