configure, meson: move symlinking of ROMs to meson

configure, meson: move symlinking of ROMs to meson

This is useful because pc-bios/meson.build already has a list of all ROM
files, and thus does not need to use wildcards.  The problems with
wildcards are mentioned above the definition of the LINKS variable,
but then the recommendation is disattended.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220517092616.1272238-6-pbonzini@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20220527153603.887929-17-alex.bennee@linaro.org>