[Object] Fix warnings

This patch fixes:

  llvm/unittests/Object/OffloadingBundleTest.cpp:56:19: error: unused
  variable 'mbuf' [-Werror,-Wunused-variable]

  llvm/unittests/Object/OffloadingBundleTest.cpp:57:13: error: unused
  variable 'FileName' [-Werror,-Wunused-variable]

  llvm/unittests/Object/OffloadingBundleTest.cpp:72:19: error: unused
  variable 'mbuf' [-Werror,-Wunused-variable]

  llvm/unittests/Object/OffloadingBundleTest.cpp:73:13: error: unused
  variable 'FileName' [-Werror,-Wunused-variable]

Author: kazutakahirata

llvm/unittests/Object/OffloadingBundleTest.cpp

@@ -51,10 +51,6 @@ toBinary(SmallVectorImpl<char> &Storage, StringRef Yaml) {
 }
 
 TEST(OffloadingBundleTest, checkExtractOffloadBundleFatBinary) {
-
-  // create a Memory Buffer with a fatbin offloading section
-  MemoryBufferRef mbuf;
-  StringRef FileName;
   SmallVector<OffloadBundleEntry>();
   SmallString<0> Storage;
   // Expected<ELFObjectFile<ELF64LE>> ObjOrErr = toBinary<ELF64LE>(Storage, R"(
@@ -68,9 +64,6 @@ TEST(OffloadingBundleTest, checkExtractOffloadBundleFatBinary) {
 }
 
 TEST(OffloadingBundleTest, checkExtractCodeObject) {
-  // create a Memory Buffer with a fatbin offloading section
-  MemoryBufferRef mbuf;
-  StringRef FileName;
   SmallVector<OffloadBundleEntry>();
   SmallString<0> Storage;
   // Expected<ELFObjectFile<ELF64LE>> ObjOrErr = toBinary<ELF64LE>(Storage, R"(