Object/COFF: Fix off-by-one error for object having lots of relocations

llvm-objdump printed out an error message for this off-by-one error,
but because it always exits with 0 whether or not it found an error,
the test (llvm-objdump/coff-many-relocs.test) succeeded.
I made llvm-objdump exit with EXIT_FAILURE when an error is found.

llvm-svn: 222852

llvm/lib/Object/COFFObjectFile.cpp

@@ -414,7 +414,8 @@ static uint32_t getNumberOfRelocations(const coff_section *Sec,
     if (getObject(FirstReloc, M, reinterpret_cast<const coff_relocation*>(
         base + Sec->PointerToRelocations)))
       return 0;
-    return FirstReloc->VirtualAddress;
+    // -1 to exclude this first relocation entry.
+    return FirstReloc->VirtualAddress - 1;
   }
   return Sec->NumberOfRelocations;
 }