illumos linker does not supprot --export-dynamic

--- gtk-4.16.6/testsuite/gtk/meson.build.orig
+++ gtk-4.16.6/testsuite/gtk/meson.build
@@ -10,6 +10,8 @@
   endif
 endif
 
+gtk_tests_export_dynamic_ldflag = []
+
 # Available keys for each test:
 #
 #  - 'name': the test name; used for the test and to determine the base