[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
diff --git a/tools/scan-build/ccc-analyzer b/tools/scan-build/ccc-analyzer
index 8717225..8bd9ec2 100755
--- a/tools/scan-build/ccc-analyzer
+++ b/tools/scan-build/ccc-analyzer
@@ -389,6 +389,7 @@
   'cxx' => 'c++',
   'txx' => 'c++',
   'cc'  => 'c++',
+  'C'   => 'c++',
   'ii'  => 'c++',
   'i'   => 'c-cpp-output',
   'm'   => 'objective-c',