Add a flag PrintingPolicy::DontRecurseInDeclContext to provide "terse" output
from DeclPrinter. The motivation is to use DeclPrinter to print declarations
in user-friendly format, without overwhelming user with inner detail of the
declaration being printed.
Also add many tests for DeclPrinter. There are quite a few things that we
print incorrectly: search for WRONG in DeclPrinterTest.cpp -- and these tests
check our output against incorrect output, so that we can fix/refactor/rewrite
the DeclPrinter later.
llvm-svn: 162245