Avoid a conflicting typedef on 32-bit arch.

Index: third_party/cmocka/include/cmocka.h
--- third_party/cmocka/include/cmocka.h.orig
+++ third_party/cmocka/include/cmocka.h
@@ -96,6 +96,9 @@ typedef uintmax_t LargestIntegralType;
 #define cast_to_largest_integral_type(value) \
     ((LargestIntegralType)(value))
 
+#if defined(__OpenBSD__)
+#include <stdint.h>
+#else
 /* Smallest integral type capable of holding a pointer. */
 #if !defined(_UINTPTR_T) && !defined(_UINTPTR_T_DEFINED)
 # if defined(_WIN32)
@@ -124,6 +127,7 @@ typedef uintmax_t LargestIntegralType;
 # define _UINTPTR_T
 # define _UINTPTR_T_DEFINED
 #endif /* !defined(_UINTPTR_T) || !defined(_UINTPTR_T_DEFINED) */
+#endif /* !defined(__OpenBSD__) */
 
 /* Perform an unsigned cast to uintptr_t. */
 #define cast_to_pointer_integral_type(value) \
