Support both hard and soft aliasing of the standard printf-family functions #141
Description
mpaland's older versions supported aliasing printf(), sprintf() and friends using macros, so that the library exposed printf_, sprintf_ etc on the lower level, the user wrote printf("foo"), and a macro translated this into printf_("foo") which then found the right symbol.
I changed this to "hard" aliasing, so that libprintf really exposes printf, sprintf etc, with no need for macros on the outside. However, apparently, for some people this is not a useful approach - see #133 . So, let's support both aliasing methods - hard and soft, actual-compiled or just-macro.