Use SIZE_T_MAX instead of ulong as a limit for key_buffer_size to allow...

Use SIZE_T_MAX instead of ulong as a limit for key_buffer_size to allow key_bufer_size > 4G on Windows in 5.1. This is for bug #5731.

include/my_global.h

@@ -863,6 +863,9 @@ typedef SOCKET_SIZE_TYPE size_socket;
 #ifndef SSIZE_MAX
 #define SSIZE_MAX ((~((size_t) 0)) / 2)
 #endif
+#ifndef SIZE_T_MAX
+#define SIZE_T_MAX ~((size_t) 0)
+#endif
 
 #ifndef HAVE_FINITE
 #define finite(x) (1.0 / fabs(x) > 0.0)

sql/mysqld.cc

@@ -5969,7 +5969,7 @@ log and this option does nothing anymore.",
    (uchar**) &dflt_key_cache_var.param_buff_size,
    (uchar**) 0,
    0, (GET_ULL | GET_ASK_ADDR),
-   REQUIRED_ARG, KEY_CACHE_SIZE, MALLOC_OVERHEAD, ~(ulong) 0, MALLOC_OVERHEAD,
+   REQUIRED_ARG, KEY_CACHE_SIZE, MALLOC_OVERHEAD, SIZE_T_MAX, MALLOC_OVERHEAD,
    IO_SIZE, 0},
   {"key_cache_age_threshold", OPT_KEY_CACHE_AGE_THRESHOLD,
    "This characterizes the number of hits a hot block has to be untouched until it is considered aged enough to be downgraded to a warm block. This specifies the percentage ratio of that number of hits to the total number of blocks in key cache",