change regex to non-capturing parentheses

shigeki · shigeki · commit ed1d266f36e5 · 2017-03-06T12:01:03.000+09:00
diff --git a/configure b/configure
@@ -576,8 +576,7 @@ def get_version_helper(cc, regexp):
 
 def get_llvm_version(cc):
   return get_version_helper(
-    cc, r"(^clang version|^FreeBSD clang version|based on LLVM) " +
-    "([3-9]\.[0-9]+)")
+    cc, r"(^(?:FreeBSD )?clang version|based on LLVM) ([3-9]\.[0-9]+)")
 
 def get_xcode_version(cc):
   return get_version_helper(
