- Also, don't print headers if we aren't going to print any diagnostics.

llvm-svn: 170973

llvm-svn: 143525

rdar://9683410

llvm-svn: 142856

If enabled, this will attempt to use the CC_LOG_DIAGNOSTICS feature I dropped
into Clang to print a log of all the diagnostics generated during an individual
build (from the top-level). Not sure if this will actually be useful, but for
now it is handy for testing the option.

llvm-svn: 129312