[sanitizers] Propagate the sanitizer options through to the lit context.

This makes it *really* easy to debug leaks FYI:

ASAN_OPTIONS=detect_leaks=1 ./bin/llvm-lit -v <path to test>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207874 91177308-0d34-0410-b5e6-96231b3b80d8

Author: chandlerc

test/lit.cfg

@@ -95,6 +95,11 @@ for symbolizer in ['ASAN_SYMBOLIZER_PATH', 'MSAN_SYMBOLIZER_PATH']:
     if symbolizer in os.environ:
         config.environment[symbolizer] = os.environ[symbolizer]
 
+# Propagate options for sanitizers.
+for options in ['ASAN_OPTIONS']:
+    if options in os.environ:
+        config.environment[options] = os.environ[options]
+
 ###
 
 import os