Add #includes for ptrdiff_t, size_t, and uint32_t.

This should help fix the Google3 roll: http://screen/9Lja4vRrpGUgjUJ

Change-Id: I3e838cc7647796a1f37de7c37b122e35aaf7eac4
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/780876
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Florin Malita <fmalita@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
diff --git a/src/skcms_Transform.h b/src/skcms_Transform.h
index 9c13e50..3401885 100644
--- a/src/skcms_Transform.h
+++ b/src/skcms_Transform.h
@@ -7,6 +7,9 @@
 
 #pragma once
 
+#include <stddef.h>
+#include <stdint.h>
+
 // skcms_Transform.h contains skcms implementation details.
 // Please don't use this header from outside the skcms repo.