[codeview] Add breaks to fix -Wimplicit-fallthrough

This is a minor bug fix. Previously, if you tried to encode the RSP
register on the x86 platform, that might have succeeded and been encoded
incorrectly. However, no existing producer or consumer passes the x86_64
registers when targeting x86_32.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@345879 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed