meson: Use files() instead of find_program() for internal scripts

Using find_program() to locate scripts part of the source tree causes
meson to print messages at setup time for each of those scripts:

Program ipa-sign.sh found: YES (/home/user/src/libcamera/src/ipa/ipa-sign.sh)

This pollutes the meson setup log with useless messages, as we know the
scripts are present. Use files() instead to avoid this.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/ipa/meson.build

@@ -16,7 +16,7 @@ config_h.set('IPA_MODULE_DIR',
 
 subdir('libipa')
 
-ipa_sign = find_program('ipa-sign.sh')
+ipa_sign = files('ipa-sign.sh')
 
 ipas = ['rkisp1', 'vimc']