Include 4 new backports

Include 4 new backports

• libmakepkg: remove MAKEFLAGS from buildenv_vars
  • pacman/pacman@027ecbc7
  • Fixes #25
• pacman-key: fix permission checks for non-root operations
  • pacman/pacman@49ebd856
  • Fixes #29
• libmakepkg: do not unset CHOST with !buildflags
  • pacman/pacman@7dcf9a2b
  • Fixes #25
• libmakepkg: add fortran buildenv to meson sources array
  • pacman/pacman@792df078
  • Fixes #28