[sr-dev] unused variable

[Juha Heinanen]

With latest master, I got this:

CC (gcc) [M db_mysql.so]		km_dbase.o
km_dbase.c: In function 'db_mysql_submit_query':
km_dbase.c:71:9: warning: unused variable 't' [-Wunused-variable]
  time_t t;
         ^

It would be nice if devs would try to compile the code after making
changes.

-- Juha