[lit] Adding config initialization to lit tests in clang-tools-extra

Adding the config initialization to clang-tools-extra so that tests that
use REQUIRES, UNSUPPORTED, and XFAIL based on platform or target triple
work properly.

Differential Revision: https://reviews.llvm.org/D44708

llvm-svn: 328060

clang-tools-extra/test/lit.site.cfg.in

@@ -23,5 +23,7 @@ except KeyError:
     key, = e.args
     lit_config.fatal("unable to find %r parameter, use '--param=%s=VALUE'" % (key,key))
 
+@LIT_SITE_CFG_IN_FOOTER@
+
 # Let the main config do the real work.
 lit_config.load_config(config, "@CLANG_TOOLS_SOURCE_DIR@/test/lit.cfg")