[Stackmaps] Update the stackmap format to use 64-bit relocations for the function address and properly align all entries.

This commit updates the stackmap format to version 1 to indicate the
reorganizaion of several fields. This was done in order to align stackmap
entries to their natural alignment and to minimize padding.

Fixes <rdar://problem/16005902>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205254 91177308-0d34-0410-b5e6-96231b3b80d8