Build changes for Solaris x86 & Sparc.

I've added the GNU tar changes, put a note in the readme saying to use gmake on Solaris and added some extra names to Makefile.common. I've tested that the native library builds on Sparc, but I don't have access to a Sparc machine with Maven so I can't test the building of the Java library. It should build given Solaris x86 builds fine.