Alterative sysprof build support

Don't link libgtk against libsysprof. We only
need that for the test-performance binary.

tests/meson.build

@@ -136,9 +136,9 @@ foreach t: gtk_tests
              dependencies: [libgtk_dep, libm])
 endforeach
 
-if get_option('profiler')
+if profiler_enabled
   executable('testperf', 'testperf.c',
-              dependencies: [profiler_dep, platform_gio_dep, libm])
+              dependencies: [libsysprof_dep, platform_gio_dep, libm])
 endif
 
 librsvg = dependency('librsvg-2.0', version: '>= 2.46.0', required: false)