Fix enviroment variables when running shell scripts

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@258217 91177308-0d34-0410-b5e6-96231b3b80d8

test/libcxx/test/config.py

@@ -615,7 +615,7 @@ class Configuration(object):
         for k, v in self.env.items():
             exec_env_str += ' %s=%s' % (k, v)
         # Configure run env substitution.
-        exec_str = ''
+        exec_str = exec_env_str
         if self.lit_config.useValgrind:
             exec_str = ' '.join(self.lit_config.valgrindArgs) + exec_env_str
         sub.append(('%exec', exec_str))