Fix breakage of native image scaling on XRENDER by previous change

* src/image.c (image_create_x_image_and_pixmap_1) [HAVE_XRENDER]: Get depth if
it is unspecified.
1 job for master in 51 minutes and 39 seconds (queued for 4 seconds)
Status Job ID Name Coverage
failed #1941


Name Stage Failure
test-all Test
make[2]: *** [check-doit] Error 1
Makefile:318: recipe for target 'check-doit' failed
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:293: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:957: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1