FT_PARSER.C:92

DESCRIPTION
===========
Starting the server with default charset as 'utf16le', and
setting system variable "ft_boolean_syntax" results in
server crash.

ANALYSIS
========
Function "ft_boolean_check_syntax_string()" uses the MACRO
"my_isalnum" which checks for the member "ctype" of the
default charset. Since this member is NULL (for charset
'utf16le') therefore when accessed, results in SEGFAULT!

We can prevent it altogether by replacing "my_isalnum"
(which depends on the default charset) with C's "isalnum()"
. Using "isalnum()" here is sufficient as the input to this
function is guaranteed to be in ASCII format.

FIX
===
Replaced user defined "my_isalnum" with C's "isalnum()"
in the function "ft_boolean_check_syntax_string()"