unittests: Fix 51 ldflagdedup on Solaris

If the linker doesn't support --export-dynamic, skip test to deduplicate
it, since it always fails finding 0 copies instead of 1.

run_unittests.py

@@ -6772,6 +6772,11 @@ class LinuxlikeTests(BasePlatformTests):
         testdir = os.path.join(self.unit_test_dir, '52 ldflagdedup')
         if is_cygwin() or is_osx():
             raise unittest.SkipTest('Not applicable on Cygwin or OSX.')
+        env = get_fake_env()
+        cc = env.detect_c_compiler(MachineChoice.HOST)
+        linker = cc.linker
+        if not linker.export_dynamic_args(env):
+            raise unittest.SkipTest('Not applicable for linkers without --export-dynamic')
         self.init(testdir)
         build_ninja = os.path.join(self.builddir, 'build.ninja')
         max_count = 0