ninja/mac: Don't link c-file-only targets to libstdc++

test/make_global_settings/env-wrapper/gyptest-wrapper.py

Index: test/make_global_settings/env-wrapper/gyptest-wrapper.py
===================================================================
--- test/make_global_settings/env-wrapper/gyptest-wrapper.py	(revision 1718)
+++ test/make_global_settings/env-wrapper/gyptest-wrapper.py	(working copy)
@@ -31,11 +31,16 @@
                  os.path.join('..', '..', 'clang'))
   cc_host_expected = ('cc_host = ' + os.path.join('..', '..', 'ccache') + ' ' +
                       os.path.join('..', '..', 'clang'))
-  ld_expected = 'ld = ../../distlink $cxx'
+  ld_expected = 'ld = ../../distlink $cc'
+  if sys.platform != 'win32':
+    ldxx_expected = 'ldxx = ../../distlink $cxx'
+
   if sys.platform == 'win32':
      ld_expected = 'link.exe'
   test.must_contain('out/Default/build.ninja', cc_expected)
   test.must_contain('out/Default/build.ninja', cc_host_expected)
   test.must_contain('out/Default/build.ninja', ld_expected)
+  if sys.platform != 'win32':
+    test.must_contain('out/Default/build.ninja', ldxx_expected)
 
 test.pass_test()