gettext: Disable --with-included-gettext Linuxbrew

Installing libintl.so causes trouble. It should be installed by glibc.
gnu-getopt 1.1.5: Do not use -lintl for Linuxbrew
glib 2.42.0: Do not use -lintl for Linuxbrew
ghc 7.4.2: Patch for Linuxbrew
git-flow-avh: fix zsh zsh_completion.
git-flow-avh: Support Linux systems.
git: only show OS X keychain caveat on OSX systems.