[tasks] Add gangdistcheck rule to check builds with all of the options

[Ross Burton <rburton src gnome org>]

commit 7702550f211fcf6c145f80551bad1fee31ae0abf
Author: Ross Burton <ross linux intel com>
Date:   Mon Mar 30 10:52:14 2009 +0100

    Add gangdistcheck rule to check builds with all of the options
---
 Makefile.am |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/Makefile.am b/Makefile.am
index 4fdde27..e8c0402 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -9,3 +9,7 @@ DISTCLEANFILES =		\
 	intltool-extract	\
 	intltool-merge		\
 	intltool-update
+
+gangdistcheck:
+	$(MAKE) DISTCHECK_CONFIGURE_FLAGS= distcheck
+	$(MAKE) DISTCHECK_CONFIGURE_FLAGS=--with-unique distcheck