[llvm-c-test] Fix warnings
This patch fixes:
llvm/tools/llvm-c-test/debuginfo.c:254:20: error: unused variable
'AddDbgRecordLast' [-Werror,-Wunused-variable]
llvm/tools/llvm-c-test/debuginfo.c:257:20: error: unused variable
'AddDbgRecordOverTheRange' [-Werror,-Wunused-variable]
llvm/tools/llvm-c-test/debuginfo.c:264:20: error: unused variable
'AddDbgRecordUnderTheRange' [-Werror,-Wunused-variable]
