make pthread_key_t unsigned to match ABI

include/alltypes.h.in

@@ -46,7 +46,7 @@ TYPEDEF unsigned long pthread_t;
 TYPEDEF struct __pthread * pthread_t;
 #endif
 TYPEDEF int pthread_once_t;
-TYPEDEF int pthread_key_t;
+TYPEDEF unsigned pthread_key_t;
 TYPEDEF int pthread_spinlock_t;
 TYPEDEF struct { unsigned __attr; } pthread_mutexattr_t;
 TYPEDEF struct { unsigned __attr; } pthread_condattr_t;