Add support for SIGRTMIN+1..SIGRTMAX-1 signals in ktruss(1)

Generate misc.c and misc.h with entries for signals between SIGRTMIN+1
and SIGRTMAX-1.

Use 'sort -n -k 3' instead of 'sort -n +2' since the former is more
portable. The latter is not supported by Mac OS X Lion.

branches: 1.5.2; 1.5.4; 1.5.8; 1.5.12; 1.5.20; 1.5.22;
In shell scripts invoked during a build, and in crunchgen, use ${AWK}
instead of plain "awk". The Makefiles that invoke these scripts
or programs will pass AWK=${HOST_AWK:Q}.

Make this build with WARNS=3, and enable it.
Renames local variable syscall to syscall_ent to placate -Wshadow,
and adds const to struct field initialized to string literals.

Use the errno.h and signal.h passed in on the command line.

Pass CPP and CPPFLAGS to makerrnos.sh, and use them. Default to cpp and
empty, respectively, if not provided.

- build with obj dirs.
- use .PATH not broken links
- share the make fragment to build "ioctl.c"
- general clean up, RCSID, etc.

this is all happy now AFAICT.