improve xcode_emulation.py

test/ios/deployment-target/check-version-min.c

+/* Copyright (c) 2013 Google Inc. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file. */
+
+#include <Availability.h>
+
+/* GYPTEST_MAC_VERSION_MIN: should be set to the corresponding value of
+ * xcode setting 'MACOSX_DEPLOYMENT_TARGET', otherwise both should be
+ * left undefined.
+ *
+ * GYPTEST_IOS_VERSION_MIN: should be set to the corresponding value of
+ * xcode setting 'IPHONEOS_DEPLOYMENT_TARGET', otherwise both should be
+ * left undefined.
+ *
+ * NOTE: At least one GYPTEST_*_VERSION_MIN *MUST* be defined.
+ */
+
+#if defined(GYPTEST_MAC_VERSION_MIN)
+# if GYPTEST_MAC_VERSION_MIN != __MAC_OS_X_VERSION_MIN_REQUIRED
+#  error __MAC_OS_X_VERSION_MIN_REQUIRED has wrong value
+# endif
+#elif defined(__MAC_OS_X_VERSION_MIN_REQUIRED)
+# error __MAC_OS_X_VERSION_MIN_REQUIRED should be undefined
+#endif
+
+#if defined(GYPTEST_IOS_VERSION_MIN)
+# if GYPTEST_IOS_VERSION_MIN != __IPHONE_OS_VERSION_MIN_REQUIRED
+#  error __IPHONE_OS_VERSION_MIN_REQUIRED has wrong value
+# endif
+#elif defined(__IPHONE_OS_VERSION_MIN_REQUIRED)
+# error __IPHONE_OS_VERSION_MIN_REQUIRED should be undefined
+#endif
+
+int main() { return 0; }
+