update WHATSNEW in preparation for release

WHATSNEW

@@ -23,11 +23,18 @@ respectively.
 many internal improvements have been made to the syscall-related code
 in preparation for porting to x86_64 and other archs.
 
-upcoming 0.6.0 - x86_64 port, header bugfixes
+upcoming 0.6.0 - x86_64 port, various important fixes
 
 new x86_64 (amd64) architecture port, contributed by Nicholas J. Kain,
 along with PORTING guide. source tree layout and build system have
 been improved to accommodate further ports.
 
 various bugs that were introduced while making the headers respect C
-and POSIX namespace standards have been fixed.
+and POSIX namespace standards have been fixed. conformance to the
+standards has been improved.
+
+fixed an inefficiency in qsort that triggered a bug (occasionaly
+internal compiler error) in some versions of gcc.
+
+fixed a major bug in the printf %n specifier that prevented it from
+working and caused memory corruption.