This patch extends the libLLVMDebugInfo which contains a minimalistic DWARF parser:

1) DIContext is now able to return function name for a given instruction address (besides file/line info).
2) llvm-dwarfdump accepts flag --functions that prints the function name (if address is specified by --address flag).
3) test case that checks the basic functionality of llvm-dwarfdump added

llvm-svn: 159512