arosc_emul.c/emul_arosc.c: Remove most of the functions from c emul code.

arosc_emul.c/emul_arosc.c: Remove most of the functions from c emul code.

The stdc.library and stdcio.library versions of the functions can be
used now.
These libraries are now peropenerbase and so modules can have their own private
libbase for these libraries.

abort() and exit() will Guru when called from a library and non appropriately
initialized. This is as good as going into endless loop.
The functions gettimeofday(), usleep() are part of posixc.library and remain
in the emul files.
The atexit() implementation for mesa also stays; maybe this should be looked at
further how this exactly has to be implemented.

For SDL.library now an internal dummy sigaction() is provided.

git-svn-id: https://svn.aros.org/svn/aros/trunk@48057 fb15a70f-31f2-0310-bbcc-cdcc74a49acc