try to rearrange libs used for linking ...

If all of that fails - libgroups are required (but I think in case of
useshrplib=false we might to skip the test at all)
put -lperl before $Config{perllibs}
rework check_prog to improve for " " in prog path

Most MSWin32 systems have "C:\Program Files...\bin\gnuprog.exe" - deal
with that even on simple progs.
re-enable cleanup at END
don't TODO -lm on non-win32
add nytprof stuff being ignored
doing some micro-optimizations

even if longest part is invoking cc, it doesn't need wasting time
note Changes for 0.304