include *any* path on crtbegin.o unless we actually find such a file via
one of the search paths. We still strictly check the search paths right
after this, so we'll catch any issues there.

The reason for this is that the driver does some normalization of the
path on the actual object file, and this changes the textual format of
the string on Windows. It no longer matches the textual format of the
sysroot flag.

llvm-svn: 140998