Merge branch 'jk/config-int-range-check'

Merge branch 'jk/config-int-range-check'

"git config" did not provide a way to set or access numbers larger
than a native "int" on the platform; it now provides 64-bit signed
integers on all platforms.

* jk/config-int-range-check:
  git-config: always treat --int as 64-bit internally
  config: make numeric parsing errors more clear
  config: set errno in numeric git_parse_* functions
  config: properly range-check integer values
  config: factor out integer parsing from range checks