Another Solaris shared build clean-up. This is not actually needed if one

Another Solaris shared build clean-up. This is not actually needed if one
uses WorkShop C. It's gcc driver that brings copy of libgcc.a into .so
otherwise. In case you wonder what it's -Wl,-z... and not just -z. Problem
is that gcc driver apparently omits all -z options but -z text. Don't ask
me why. I'm not committing corresponding workaround into the HEAD as
Makefile.shared reportedly needs even more work...