max > nelem(stk) is wrong.  should be >=; change to assert.

Reference: /n/sources/patch/applied/mpfact-ineq
Date: Thu Jan  5 20:49:05 CET 2012
Signed-off-by: quanstro@quanstro.net

--- /sys/src/libmp/port/mpfactorial.c	Thu Jan  5 20:48:35 2012
+++ /sys/src/libmp/port/mpfactorial.c	Thu Jan  5 20:48:33 2012
@@ -42,8 +42,7 @@
 				max++;
 				if(max > mmax){
 					mmax++;
-					if(max > nelem(stk))
-						abort();
+					assert(max < nelem(stk));
 					stk[max] = mpnew(Dbits);
 				}
 				stk[max]->top = 1;