Fix some Mac OS size_t versus int complaints.

Change-Id: I80bd0737122e76b42090fa0eed9b3f7c33b3640b
diff --git a/src/class_linker.cc b/src/class_linker.cc
index df2e971..4d3b2ea 100644
--- a/src/class_linker.cc
+++ b/src/class_linker.cc
@@ -2301,7 +2301,7 @@
     // No vtable.
     size_t count = klass->NumVirtualMethods();
     if (!IsUint(16, count)) {
-      ThrowClassFormatError("Too many methods on interface: %d", count);
+      ThrowClassFormatError("Too many methods on interface: %zd", count);
       return false;
     }
     for (size_t i = 0; i < count; ++i) {
@@ -2355,7 +2355,7 @@
       }
     }
     if (!IsUint(16, actual_count)) {
-      ThrowClassFormatError("Too many methods defined on class: %d", actual_count);
+      ThrowClassFormatError("Too many methods defined on class: %zd", actual_count);
       return false;
     }
     // Shrink vtable if possible