Removing potentially error-prone fallthrough. NFC

This fallthrough if other cases are added between fabs and default
could cause fabs to fall to the next case resulting in a bug.
Better getting rid of it immediately just to be sure.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@292003 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed