eina_log: be able to disable function or line.

eina_log: be able to disable function or line.

write down specialized cases for threads or not, function or file,
color or not. Maybe it's not even an optimization since we add yet
another indirection/function call, but each case is simpler.

 * EINA_LOG_FILE_DISABLE=1: disables show of file:line in
   stderr/stdout messages.
 * EINA_LOG_FUNCTION_DISABLE=1: disables show of function() in
   stderr/stdout messages.

one must not use the two options at the same time, if that's the case
code will ignore EINA_LOG_FILE_DISABLE=1 and use just function
disable.

git-svn-id: svn+ssh://svn.enlightenment.org/var/svn/e/trunk/eina@42272 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33