[Vortex] Bug: double free of vortex_ctx

[Jens Alfke]

There seems to be a bug in vortex.c that causes the vortex_ctx to be  
freed twice if vortex_dtds_init fails. I discovered this due to a  
double-free warning from malloc. The sequence of events is:

- vortex_init calls vortex_init_ctx
	- vortex_init_ctx calls vortex_dtds_init
		- that function returns false
	- so vortex_init_ctx calls vortex_ctx_free (vortex.c:899) and returns  
false
- vortex_init calls vortex_ctx_free again (vortex.c:793)

My guess is that the line vortex.c:899 should be deleted, because  
there are other paths out of that function that return false but do  
not free the context.

(The line numbers are from SVN rev 3194.)

--Jens