Declare functions with EXTINLINE:

* mpd_del()
* mpd_uint_zero()
* mpd_qresize()
* mpd_qresize_zero()
* mpd_minalloc()

These functions are implemented with "inline" or "ALWAYS_INLINE", but
declared without inline which cause linker error on Visual Studio in
Debug mode when using /Ob1.
(cherry picked from commit 3b1cba37)
Co-authored-by: Victor Stinner <vstinner@redhat.com>