Merge branch 'jk/squelch-compiler-warning-from-funny-error-macro'

* jk/squelch-compiler-warning-from-funny-error-macro:
  let clang use the constant-return error() macro
  inline constant return from error() function

diff --cc cache.h
Simple merge

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

diff --cc parse-options.h
Simple merge