[analyzer] scan-build: Treat '.C' files as C++.

Part of PR14443.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@168804 91177308-0d34-0410-b5e6-96231b3b80d8

tools/scan-build/ccc-analyzer

@@ -389,6 +389,7 @@ my %LangMap = (
   'cxx' => 'c++',
   'txx' => 'c++',
   'cc'  => 'c++',
+  'C'   => 'c++',
   'ii'  => 'c++',
   'i'   => 'c-cpp-output',
   'm'   => 'objective-c',