produce hex digits in lower case). (fixed version)

Replaced _dig_vec array with two _dig_vec_upper/_dig_vec_lower arrays.
Added extra argument to int2str function which controls case of digits you get.
Replaced lot of invocations of int2str for decimal radix with more optimized int10_to_str()
function.
Removed unused my_itoa/my_ltoa functions.


client/mysql.cc:
  Replaced int2str invocations with radix argument equal to 10 with optimized int10_to_str()
  call.
client/mysqladmin.c:
  Replaced int2str invocations with radix argument equal to 10 with optimized int10_to_str()
  call.
dbug/dbug.c:
   _dig_vec became _dig_vec_upper.
include/m_string.h:
  _dig_vec is obsoleted by _dig_vec_upper/_dig_vec_lower.
  my_itoa()/my_ltoa() functions were removed because they were never used in our code.
  int2str() now has one more argument which controls case of digits it will produce.
include/my_global.h:
  my_itoa()/my_ltoa() functions were removed because they were never used in our code.
isam/isamchk.c:
  Replaced int2str invocations with radix argument equal to 10 with optimized int10_to_str()
  call.
libmysql/libmysql.def:
  _dig_vec is obsoleted by _dig_vec_upper/_dig_vec_lower.
myisam/myisamchk.c:
  Replaced int2str invocation with radix argument equal to 10 with optimized int10_to_str()
  call.
mysys/mf_tempfile.c:
  _dig_vec became _dig_vec_upper.
mysys/my_error.c:
  Replaced int2str invocations with radix argument equal to 10 with optimized int10_to_str()
  call.
mysys/my_tempnam.c:
  _dig_vec became _dig_vec_upper.
sql-common/client.c:
  Replaced int2str invocation with radix argument equal to 10 with optimized int10_to_str()
  call.
sql/item_strfunc.cc:
  _dig_vec became _dig_vec_upper. Also we don't need hex[] array in this file now because we
  have _dig_vec_lower instead.
sql/mysqld.cc:
  Replaced int2str invocations with radix argument equal to 10 with optimized int10_to_str()
  call.
sql/password.c:
  _dig_vec became _dig_vec_upper.
sql/sql_bitmap.h:
  _dig_vec became _dig_vec_upper.
strings/int2str.c:
  Replaced _dig_vec by _dig_vec_upper/_dig_vec_lower pair.
  int2str() now has one more argument which controls case of digits it will produce.
  my_itoa()/my_ltoa() functions were removed because they were never used in our code.
strings/longlong2str-x86.s:
  _dig_vec became _dig_vec_upper.
strings/longlong2str.c:
  _dig_vec became _dig_vec_upper.
strings/my_vsnprintf.c:
  If my_snprintf() is printing %x argument it should produce lower case hexadecimal digits
  to be snprintf() compatible.