package/pkg-meson.mk: fix multiple _MESON_EXTRA_BINARIES

package/pkg-meson.mk: fix multiple _MESON_EXTRA_BINARIES

If multiple entries are specified for _MESON_EXTRA_BINARIES, the current
sed expression will only replace the first one.

Specifically, from GNU sed 4.8 the manual says:

    /regexp/
        Match  lines matching the regular expression regexp.  Matching
        is performed on the current pattern space, which can be modified
        with commands such as ``s///''.

so after the first binary has been added, the next entry no longer
matches since the pattern space has been modifed.

Instead of adding a script for each value, apply the match once and add
a subsitution for all entries at once.

Signed-off-by: John Keeping <john@metanate.com>
Tested-by: Peter Seiderer <ps.report@gmx.net>
[yann.morin.1998@free.fr: do a single substitution]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>