sync with the regular method; no functional diff
remove unused prototypes
PR/49287: David Holland: Skip the right number of bytes to go over the first
argument in the argv vector. Fixes netbsd32 script execution, where you lost
the first argument because it skipped 8 bytes instead of 4.
Back out previous until it can be fixed - it was causing all
sets to contain all files, which made a full build of all arches
over 150GB!

My awk isn't good enough to fix this myself in the time available.
Don't overwrite the real unwind.h if it is present.
HAVE_GCC might not be defined at all...