Backporting WL#3759 Optimize identifier conversion in client-server protocol

This patch provides performance improvements:
- send_fields() when character_set_results = latin1
  is now about twice faster for column/table/database
  names, consisting on ASCII characters.

Changes:

- Protocol doesn't use "convert" temporary buffer anymore,
  and converts strings directly to "packet".

- General conversion optimization: quick conversion
  of ASCII strings was added.

modified files:

include/m_ctype.h
- Adding a new flag.
- Adding a new function prototype

libmysqld/lib_sql.cc
- Adding quick conversion method for embedded library:
  conversion is now done directly to result buffer,
  without using a temporary buffer.

mysys/charset.c
- Mark all dynamic ucs2 character sets as non-ASCII
- Mark some dymamic 7bit and 8bit charsets as non-ASCII
  (for example swe7 is not fully ASCII compatible).

sql/protocol.cc
- Adding quick method to convert a string directly
  into protocol buffer, without using a temporary buffer.

sql/protocol.h
- Adding a new method prototype

sql/sql_string.cc
  Optimization for conversion between two ASCII-compatible charsets:
- quickly convert ASCII strings,
  switch to mc_wc->wc_mb method only when a non-ASCII character is met.
- copy four ASCII characters at once on i386

strings/conf_to_src.c
- Marking non-ASCII character sets with a flag.

strings/ctype-extra.c
- Regenerating ctype-extra.c by running "conf_to_src".

strings/ctype-uca.c
- Marking UCS2 character set as non-ASCII.

strings/ctype-ucs2.c
- Marking UCS2 character set as non-ASCII.

strings/ctype.c
- A new function to detect if a 7bit or 8bit character set
  is ascii compatible.

include/m_ctype.h

@@ -87,6 +87,7 @@ extern MY_UNI_CTYPE my_uni_ctype[256];
 #define MY_CS_CSSORT	1024   /* if case sensitive sort order   */	
 #define MY_CS_HIDDEN	2048   /* don't display in SHOW          */	
 #define MY_CS_PUREASCII 4096   /* if a charset is pure ascii     */
+#define MY_CS_NONASCII  8192   /* if not ASCII-compatible        */
 #define MY_CHARSET_UNDEFINED 0
 
 /* Character repertoire flags */
@@ -474,6 +475,7 @@ my_bool my_charset_is_ascii_based(CHARSET_INFO *cs);
 my_bool my_charset_is_8bit_pure_ascii(CHARSET_INFO *cs);
 uint my_charset_repertoire(CHARSET_INFO *cs);
 
+my_bool my_charset_is_ascii_compatible(CHARSET_INFO *cs);
 
 #define	_MY_U	01	/* Upper case */
 #define	_MY_L	02	/* Lower case */