hurd: Fix build

  * debian/sysdeps/hurd.mk: Do not add libpthread add-on since add-ons
    mechanism is no more.
  * debian/patches/hurd-i386/git-jmp_buf-macros.h.diff: New patch to fix
    build.
  * debian/patches/hurd-i386/libpthread_build.diff: Add more Implies to fix
    build.  Drop deprecated internal_function.
  * debian/patches/hurd-i386/libpthread_includes.diff: Move headers for
    sysdeps to find them.
  * debian/patches/hurd-i386/git-glob64.diff: Fix glob symlink compatibility
    for GNU.
  * debian/patches/hurd-i386/git-hidden-def.diff: Fix reference to rtld hidden
    symbol.
  * debian/patches/hurd-i386/git-math-ulps-i386-update.diff: Update ULPs.
  * debian/patches/hurd-i386/git-glob-PATH_MAX.diff: Fix posix glob test hurd build.