forward RTL_CONTEXT_foo logging to SAL_INFO in default debugging

Hi,

please note:

 https://gerrit.libreoffice.org/#/c/3421/

and raise any violent opposition to this move here, if there is no such
opposition on the ESC call, Im going to push it tommorrow.

The rationale (beyond what is in the commit message) is as follows:
- manually replacing RTL_CONTEXT_foo to SAL_INFO might add some additional
  context (I would file that as an EasyHack) and sort the message into a proper
  SAL_LOG area
- this move makes the the messages available at all in SAL_LOG, which is better
  than nothing 

So:
- is anyone opposing this change now as an intermediate move?
- is anyone opposing killing RTL_CONTEXT_foo in the long term as suggested by
  sberg in the comment?

Best,

Bjoern