This patch changes the system mk scripts to enable compilation
of programs using the BSD make system to compile with the new
libc.
In details, it does the following:
- it always defines the __MINIX make variable. This can be used,
in porting applications, to specialize Makefiles for Minix.
- If the environment variable NBSD is set to something different
than 'no' and if the compiler is not ack, set NBSD_LIBC to 'yes'.
This will set the destination lib directory to '/usr/netbsd/lib'
and set up CPPFLAGS and LDFLAGS to use new libc's includes and
library directory.
