[DebugInfo] Fix for split dwarf test on Windows (NFC)

On Windows, %llc_dwarf automatically adds -mtriple causing this test to
error. Changed %llc_dwarf to llc.

Differential Revision: https://reviews.llvm.org/D45869

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@330414 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed