gsk: Fall back to cairo if compiling shaders fails

There was already some fallback in place here, but
in other places we were just asserting.
9 jobs for matthiasc/for-master in 34 minutes and 42 seconds (queued for 1 second)
Status Job ID Name Coverage
  .Pre
failed #675769
allowed to fail
style-check-diff

00:02:09

 
  Build
passed #675770
fedora-x86_64

00:13:19

passed #675772
win32
msys2-mingw32

00:06:42

passed #675771
release-build

00:05:57

 
  Analysis
passed #675773
static-scan

00:12:48

 
  Docs
passed #675774
reference

00:06:24

 
  Flatpak
manual #675775
flatpak allowed to fail manual
flatpak-manual:demo
manual #675777
flatpak allowed to fail manual
flatpak-manual:icon-browser
manual #675776
flatpak allowed to fail manual
flatpak-manual:widget-factory
 
Name Stage Failure
failed
style-check-diff .Pre
+        g_clear_pointer (&programs, gsk_gl_renderer_programs_unref);                        \
+ goto out; \
+ } \
+ } \
+ G_STMT_END

#define INIT_COMMON_UNIFORM_LOCATION(program_ptr, uniform_basename) \
G_STMT_START{\
ERROR: Job failed: exit code 1