perl 5.003_03: hints/next_4.sh

perl 5.003_03: hints/next_4.sh

Get rid of extraneous isnext_4 variable.  Configure and
Makefile.SH will use $osname and $osvers instead.

Build up $mab dynamically based on available architectures.

Absorb $mab into ccflags and ccdlflags.  I hope that will
cover everything.  (Configure should automatically remove
the -arch stuff from cppflags.)

Configure now knows next4 needs to use a shared libperl.5.so.

Allow users to use -Dprefix.