Removed compiler confusing setjmp() call

In pseudo_seed(), we removed a call to setjmp() that was only
there to add more information to mix into the seed.  For compilers
such as gcc that used -Wclobbered, the call to setjmp() gave the
impression that the hash_val might be clobbered by a longjmp().
Where there is no longjmp() that would use the previous setjmp(),
the gcc compiler has nil ways to notice that. So to avoid confusion
we removed the setjmp() call.  Thanks to <GitHub user mattdm> for
raising this potential concern.

seed.c

@@ -592,7 +592,6 @@ pseudo_seed(void)
     sdata.size = sizeof(sdata);
     sdata.prev_hash64_copy = prev_hash64;	/* load previous hash */
     sdata.call_count_copy = ++call_count;	/* update call count */
-    (void) setjmp(sdata.env);
 #if defined(HAVE_ENVIRON)
     sdata.environ_copy = environ;
 #endif /* HAVE_ENVIRON */