[SR-11164] Use the toolchain's Block.h

(cherry picked from commit a7fa38f)

Author: kevints

Utilities/build-script-helper.py

@@ -26,7 +26,11 @@ def get_swiftpm_options(args):
   if platform.system() != 'Darwin':
     swiftpm_args += [
       # Dispatch headers
-      '-Xcxx', '-I', '-Xcxx', os.path.join(args.toolchain, 'usr', 'lib', 'swift'),
+      '-Xcxx', '-I', '-Xcxx',
+      os.path.join(args.toolchain, 'usr', 'lib', 'swift'),
+      # For <Block.h>
+      '-Xcxx', '-I', '-Xcxx',
+      os.path.join(args.toolchain, 'usr', 'lib', 'swift', 'Block'),
     ]
 
   return swiftpm_args
@@ -69,4 +73,4 @@ def add_common_args(parser):
     assert False, 'unknown action \'{}\''.format(args.action)
 
 if __name__ == '__main__':
-  main()
+  main()