meson: Only build gallium state tracker tests with shared_glapi

This has always been a requirement, it's just somehow been missed in the
meson build.

Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>

src/meson.build

@@ -82,7 +82,7 @@ if with_gallium
   subdir('gallium')
   # This has to be here since it requires libgallium, and subdir cannot
   # contain ..
-  if with_tests
+  if with_tests and with_shared_glapi
     subdir('mesa/state_tracker/tests')
   endif
 endif