Define the path to llvm-symbolizer tool in a common config to reduce copy-paste

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@185286 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/lit.common.cfg b/lib/lit.common.cfg
index dd67295..b19d687 100644
--- a/lib/lit.common.cfg
+++ b/lib/lit.common.cfg
@@ -40,6 +40,9 @@
 path = os.path.pathsep.join((llvm_tools_dir, config.environment['PATH']))
 config.environment['PATH'] = path
 
+# Define path to external llvm-symbolizer tool.
+config.llvm_symbolizer_path  = os.path.join(llvm_tools_dir, "llvm-symbolizer")
+
 # Use ugly construction to explicitly prohibit "clang", "clang++" etc.
 # in RUN lines.
 config.substitutions.append(