Initial 64 bit direct object support.

Initial 64 bit direct object support.

This patch allows llvm to recognize that a 64 bit object file is being produced
and that the subsequently generated ELF header has the correct information.

The test case checks for both big and little endian flavors.

Patch by Jack Carter.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153889 91177308-0d34-0410-b5e6-96231b3b80d8