Intoduce '-analyzer-checker-help' flag which outputs a list of all available static analyzer checkers.

This is pretty basic for now, eventually checkers should be grouped according to package, hidden checkers should be indicated etc.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126454 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/FrontendTool/ExecuteCompilerInvocation.cpp b/lib/FrontendTool/ExecuteCompilerInvocation.cpp
index 4bb85e7..65fad6d 100644
--- a/lib/FrontendTool/ExecuteCompilerInvocation.cpp
+++ b/lib/FrontendTool/ExecuteCompilerInvocation.cpp
@@ -108,6 +108,12 @@
     return 0;
   }
 
+  // Honor -analyzer-checker-help.
+  if (Clang->getAnalyzerOpts().ShowCheckerHelp) {
+    ento::printCheckerHelp(llvm::outs());
+    return 0;
+  }
+
   // Honor -version.
   //
   // FIXME: Use a better -version message?