Merge branch 'dm/port2zos'

z/OS port

* dm/port2zos:
  compat/bswap.h: detect endianness from XL C compiler macros
  Makefile: reorder linker flags in the git executable rule
  git-compat-util.h: support variadic macros with the XL C compiler

diff --cc Makefile
Simple merge

diff --cc git-compat-util.h
Simple merge