[PATCH] MC: Improve the .fill directive's compatibility with GAS

[David Majnemer]

  Powers-of-two were affected because MCAsmStreamer::EmitValueImpl used to directly handle the case where emission of an eight byte value occurred on a targets which don't have 64-bit directives by splitting it into two 32-bit directives.

  Because my change used more general logic to handle the same problem, I felt that it would be redundant to have the old code.

  If it's a deal breaker, I could add the old 64-bit to two 32-bit directives code back.

http://llvm-reviews.chandlerc.com/D2667