memcpy_overlap() removed, as

  1. it's wrong to use memcpy() for overlapped areas;
  2. we use it only once.
During merge to 4.1 will remove a memcpy_overlap() call 
from strings/ctype-tis620.c as well in order to fix 
bug #10836: ctype_tis620 test failure with ICC-compiled binaries on IA64.

include/m_string.h

@@ -119,16 +119,6 @@ extern	void bmove_allign(gptr dst,const gptr src,uint len);
 #define bmove512(A,B,C) memcpy(A,B,C)
 #endif
 
-#ifdef HAVE_purify
-#include <assert.h>
-#define memcpy_overlap(A,B,C) \
-DBUG_ASSERT((A) <= (B) || ((B)+(C)) <= (A)); \
-bmove((byte*) key,(byte*) from,(size_t) length);
-#else
-#define memcpy_overlap(A,B,C) memcpy((A), (B), (C))
-#endif /* HAVE_purify */
-
-
 	/* Prototypes for string functions */
 
 #if !defined(bfill) && !defined(HAVE_BFILL)

myisam/mi_search.c

@@ -1306,7 +1306,7 @@ uint _mi_get_binary_pack_key(register MI_KEYDEF *keyinfo, uint nod_flag,
     }
     DBUG_PRINT("info",("key: %p  from: %p  length: %u",
 		       key, from, length));
-    memcpy_overlap((byte*) key, (byte*) from, (size_t) length);
+    memmove((byte*) key, (byte*) from, (size_t) length);
     key+=length;
     from+=length;
   }