[gn] port 305c413

Not sure if this is everything; looks like only asan tests might be
hooked up in the GN build.

Author: nico

llvm/utils/gn/secondary/compiler-rt/test/asan/BUILD.gn

@@ -23,9 +23,15 @@ write_cmake_config("lit_site_cfg") {
     "LIT_SITE_CFG_IN_HEADER=## Autogenerated from $input, do not edit",
   ]
   if (host_os == "mac") {
-    values += [ "ASAN_TEST_DYNAMIC=1" ]
+    values += [
+      "ASAN_TEST_APPLE_TARGET_IS_HOST_PYBOOL=1",
+      "ASAN_TEST_DYNAMIC=1",
+     ]
   } else {
-    values += [ "ASAN_TEST_DYNAMIC=0" ]
+    values += [
+      "ASAN_TEST_APPLE_TARGET_IS_HOST_PYBOOL=0",
+      "ASAN_TEST_DYNAMIC=0",
+    ]
   }
 }