Documentation update: Remove NEWS, README.Solaris, update README.md

* README.Solaris is obsolete and related code has been removed
* NEWS file was unmaintained for more than a decade, remove it
* Remove "Performance" chapter about 550MHz Athlon
* gengetopt is no longer needed for ggsn
* remove compilation/installation instructions horribly out of date
* command line syntax of 'ggsn' program has changed

Change-Id: I45d627911503c7b733cae6a1396ca4d69a9994db
diff --git a/Makefile.am b/Makefile.am
index 1d7eaba..517e265 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -10,6 +10,6 @@
 dist-hook:
 	echo $(VERSION) > $(distdir)/.tarball-version
 
-EXTRA_DIST = git-version-gen .version README.md README.FreeBSD README.MacOSX README.Solaris
+EXTRA_DIST = git-version-gen .version README.md README.FreeBSD README.MacOSX
 
 @RELMAKE@