tools: patch gyp to avoid xcrun errors

Previously running ./configure with only the Xcode Command Line Tools
installed would give:

xcrun: error: unable to lookup item 'PlatformPath' from command line tools installation
xcrun: error: unable to lookup item 'PlatformPath' in SDK '/'

Co-authored-by: Ben Noordhuis <info@bnoordhuis.nl>
Fixes: nodejs/node#12531

PR-URL: nodejs/node#21520
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

gyp/pylib/gyp/xcode_emulation.py

@@ -233,6 +233,9 @@ def _IsIosWatchKitExtension(self):
   def _IsIosWatchApp(self):
     return int(self.spec.get('ios_watch_app', 0)) != 0
 
+  def _IsXCTest(self):
+    return int(self.spec.get('mac_xctest_bundle', 0)) != 0
+
   def GetFrameworkVersion(self):
     """Returns the framework version of the current target. Only valid for
     bundles."""
@@ -568,6 +571,11 @@ def GetCflags(self, configname, arch=None):
 
     cflags += self._Settings().get('WARNING_CFLAGS', [])
 
+    if self._IsXCTest():
+      platform_root = self._XcodePlatformPath(configname)
+      if platform_root:
+        cflags.append('-F' + platform_root + '/Developer/Library/Frameworks/')
+
     if sdk_root:
       framework_root = sdk_root
     else:
@@ -831,6 +839,11 @@ def GetLdflags(self, configname, product_dir, gyp_to_build_path, arch=None):
     for directory in framework_dirs:
       ldflags.append('-F' + directory.replace('$(SDKROOT)', sdk_root))
 
+    if self._IsXCTest():
+      platform_root = self._XcodePlatformPath(configname)
+      if platform_root:
+        cflags.append('-F' + platform_root + '/Developer/Library/Frameworks/')
+
     is_extension = self._IsIosAppExtension() or self._IsIosWatchKitExtension()
     if sdk_root and is_extension:
       # Adds the link flags for extensions. These flags are common for all