Fix typos in C comments inside sql/

sql/sql_string.cc

@@ -64,7 +64,7 @@ bool Binary_string::real_alloc(size_t length)
        null character is inserted at the appropriate position.
 
    - If the String does not keep a private buffer on the heap, such a buffer
-     will be allocated and the string copied accoring to its length, as found
+     will be allocated and the string copied according to its length, as found
      in String::length().
  
    For C compatibility, the new string buffer is null terminated if it was
@@ -340,7 +340,7 @@ bool String::needs_conversion(size_t arg_length,
   Checks that the source string can just be copied to the destination string
   without conversion.
   Unlike needs_conversion it will require conversion on incoming binary data
-  to ensure the data are verified for vailidity first.
+  to ensure the data are verified for validity first.
 
   @param arg_length   Length of string to copy.
   @param from_cs      Character set to copy from
@@ -385,7 +385,7 @@ bool String::needs_conversion_on_storage(size_t arg_length,
   cs			Character set for 'str'
 
   NOTES
-    For real multi-byte, ascii incompatible charactser sets,
+    For real multi-byte, ascii incompatible character sets,
     like UCS-2, add leading zeros if we have an incomplete character.
     Thus, 
       SELECT _ucs2 0xAA 
@@ -953,7 +953,7 @@ String *copy_if_not_alloced(String *to,String *from,uint32 from_length)
       "from" typically points to a temporary buffer inside Item_xxx::val_str(),
       or to Item::str_value, and thus is "less permanent" than "to".
 
-      Reallocating "to" may give more benifits:
+      Reallocating "to" may give more benefits:
       - "to" can point to a "more permanent" storage and can be reused
         for multiple rows, e.g. str_buffer in Protocol::send_result_set_row(),
         which is passed to val_str() for all string type rows.