Solaris: make -Duse64bitall'ed to have an archname of

Solaris: make -Duse64bitall'ed to have an archname of
sun4-solaris-64, from Alan Burlison.  (The default is to not
to suffix anything with -Duse64bitall if longs are 64 bit.
This may lead into confusion and much sorrow if 32-bit binaries
and 64-bit binaries are installed under the same directories.
Why is "-64" or something like that the default?  Well, there
are platforms where 64 bits really is the default default.
There adding a "-64" would be kind of odd.  Better to let
each 64-bit capable platform to choose their archnames.)

p4raw-id: //depot/perl@19380