patch fixing after review on patch-fixing of

Bug #5492 
"set @@session.read_rnd_buffer_size=33554432" crashes server on query

1. added warning comments for uint3korr (need one more byte allocated)
2. unsigned long in uint3korr was replaced by unsigned int to 
   avoid problems on 64-bits platforms
3. shorten warning comments in init_rr_cache in sql/records.cc

include/config-win.h

@@ -218,7 +218,13 @@ inline double ulonglong2double(ulonglong value)
 				  ((uint32) (uchar) (A)[0])))
 #define sint4korr(A)	(*((long *) (A)))
 #define uint2korr(A)	(*((uint16 *) (A)))
-#define uint3korr(A)	(long) (*((unsigned long *) (A)) & 0xFFFFFF)
+/*
+   ATTENTION !
+   
+    Please, note, uint3korr reads 4 bytes (not 3) !
+    It means, that you have to provide enough allocated space !
+*/
+#define uint3korr(A)	(long) (*((unsigned int *) (A)) & 0xFFFFFF)
 #define uint4korr(A)	(*((unsigned long *) (A)))
 #define uint5korr(A)	((ulonglong)(((uint32) ((uchar) (A)[0])) +\
 				    (((uint32) ((uchar) (A)[1])) << 8) +\

include/my_global.h

@@ -898,7 +898,13 @@ typedef char		bool;	/* Ordinary boolean values 0 1 */
 				  (((uint32) ((uchar) (A)[1])) << 8) +\
 				  (((uint32) ((uchar) (A)[2])) << 16))
 #else
-#define uint3korr(A)	(long) (*((unsigned long *) (A)) & 0xFFFFFF)
+/*
+   ATTENTION !
+   
+    Please, note, uint3korr reads 4 bytes (not 3) !
+    It means, that you have to provide enough allocated space !
+*/
+#define uint3korr(A)	(long) (*((unsigned int *) (A)) & 0xFFFFFF)
 #endif
 #define uint4korr(A)	(*((unsigned long *) (A)))
 #define uint5korr(A)	((ulonglong)(((uint32) ((uchar) (A)[0])) +\

sql/records.cc

@@ -249,12 +249,7 @@ static int init_rr_cache(READ_RECORD *info)
   rec_cache_size=info->cache_records*info->reclength;
   info->rec_cache_size=info->cache_records*info->ref_length;
 
-  /*
-      We are going to read the last three bytes of the buffer via uint3korr
-      This macro reads actually 4 bytes (for speed)
-      So, we have to allocate one more byte at the end of the buffer 
-      to avoid memory assertion fault 
-  */
+  // We have to allocate one more byte to use uint3korr (see comments for it)
   if (info->cache_records <= 2 ||
       !(info->cache=(byte*) my_malloc_lock(rec_cache_size+info->cache_records*
 					   info->struct_length+1,