Revert "Fix Bug 30978 by emitting cv file checksums."

This reverts commit 6389e7aa724ea7671d096f4770f016c3d86b0d54.

There is a bug in this implementation where the string value of the
checksum is outputted, instead of the actual hex bytes.  Therefore the
checksum is incorrect, and this prevent pdbs from being loaded by visual
studio.  Revert this until the checksum is emitted correctly.

llvm-svn: 313431