Streamline LTO getComdat invocation (NFC)

We already have obtained a pointer to the underlying GlobalObject,
use it directly to find the comdat, rather than using the
GlobalValue::getComdat which will do the same thing again.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279856 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed