memcache_debug() turns on debug output if parameter
on_off is equal to TRUE and turns off if it's
FALSE.
Note: memcache_debug() is accessible only if PHP was built
with --enable-debug option and always returns TRUE in this case.
Otherwise, this function has no effect and always returns FALSE.
Parameters
on_off
Turns debug output on if equals to TRUE.
Turns debug output off if equals to FALSE.
Return Values
Returns TRUE if PHP was built with --enable-debug option, otherwise
returns FALSE.
