pw_varint: Add missing includes

Change-Id: I129c5dbabcbf3c25ad72773bcc1d1d42c6ec60ef
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/98906
Pigweed-Auto-Submit: Dennis Kormalev <denk@google.com>
Reviewed-by: Armando Montanez <amontanez@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/pw_varint/public/pw_varint/varint.h b/pw_varint/public/pw_varint/varint.h
index 9d0e0ce..a71410e 100644
--- a/pw_varint/public/pw_varint/varint.h
+++ b/pw_varint/public/pw_varint/varint.h
@@ -70,6 +70,7 @@
 
 }  // extern "C"
 
+#include <limits>
 #include <span>
 #include <type_traits>
 
diff --git a/pw_varint/varint.cc b/pw_varint/varint.cc
index 0eadab3..4ae65cd 100644
--- a/pw_varint/varint.cc
+++ b/pw_varint/varint.cc
@@ -15,6 +15,7 @@
 #include "pw_varint/varint.h"
 
 #include <algorithm>
+#include <cstddef>
 
 namespace pw {
 namespace varint {