modinfo runs the preprocessor and therefore needs all generated input files
to be there.  The "depends" clause does not work in Meson 0.55.3, so for
now use "input".

Part #2: Update the rule for target-specific modules too.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-Id: <20210723120156.1183920-1-kraxel@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>