Add AST Matchers for CXXConstructorDecl::isDelegatingConstructor and CXXMethodDecl::isUserProvided.

Summary: Added two AST matchers: isDelegatingConstructor for CXXConstructorDecl::IsDelegatingConstructor; and isUserProvided corresponding to CXXMethodDecl::isUserProvided.

Reviewers: aaron.ballman, alexfh

Subscribers: klimek, cfe-commits

Patch by Michael Miller!

Differential Revision: http://reviews.llvm.org/D19038

llvm-svn: 266189