Recommit r363298 "[lit] Disable test on darwin when building shared libs."

Was reverted in r363379 due to build breakage.

Thanks to Nico Weber for reverting the original and suggesting the
fix.

Please see https://reviews.llvm.org/D61697

llvm-svn: 363502

clang/test/Tooling/clang-check-mac-libcxx-fixed-compilation-db.cpp

@@ -16,5 +16,7 @@
 //
 // ^ -ccc-install-dir passed to unbreak tests on *BSD where
 //   getMainExecutable() relies on real argv[0] being passed
+//
+// UNSUPPORTED: enable_shared
 #include <mock_vector>
 vector v;

clang/test/lit.cfg.py

@@ -183,3 +183,6 @@ if macOSSDKVersion is not None:
 
 if os.path.exists('/etc/gentoo-release'):
     config.available_features.add('gentoo')
+
+if config.enable_shared:
+    config.available_features.add("enable_shared")