Bug #16978278 : BUFFER OVERFLOW WHEN PRINTING A LARGE 64-BIT INTEGER

WITH MY_B_VPRINTF()

[Merge from 5.1]

mysys/mf_iocache2.c

@@ -419,7 +419,7 @@ process_flags:
     {
       register int iarg;
       size_t length2;
-      char buff[17];
+      char buff[32];
 
       iarg = va_arg(args, int);
       if (*fmt == 'd')
@@ -454,7 +454,7 @@ process_flags:
     {
       register long iarg;
       size_t length2;
-      char buff[17];
+      char buff[32];
 
       iarg = va_arg(args, long);
       if (*++fmt == 'd')