vlc: avoid that AUTORECONF renames configure's arguments

VLC defines two autoconf functions which are also defined by our own
pkg.m4 from pkgconf. Unfortunately, they are defined in a different way:
VLC adds --enable- options, but pkg.m4 adds --with- options. To make
sure we use VLC's definition, rename these two functions from
PKG_WITH_MODULES to VLC_PKG_WITH_MODULES and from PKG_HAVE_WITH_MODULES
to VLC_PKG_HAVE_WITH_MODULES.

Note that the second function (PKG_HAVE_WITH_MODULES) is in fact
defined in exactly the same way by VLC and pkgconf, but this might no
longer be the case when either pkgconf or VLC is updated. Therefore,
that one is renamed as well.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Acked-by: Simon Dawson <spdawson@gmail.com>
Tested-by: Simon Dawson <spdawson@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>