[Support] Extend SLEB128 encoding support.

Add support for padded SLEB128 values, and support for writing SLEB128
values to buffers rather than to ostreams, similar to the existing
ULEB128 support.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294675 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed