The change in nsec() not to cache fds broke cpp.
The problem is in cpp, not in nsec. Because it checks if
fd <= 0 and, somehow, it's called with 0 closed from the ape
framework. Now that we don't have hidden open fds, open returns 0
and ape thinks a file does not exist.
I think this fixes the problem.

Reference: /n/patches.lsub.org/patch/cppnsec
Date: Thu Apr 19 11:51:16 CES 2012
Signed-off-by: nemo@lsub.org

--- /sys/src/cmd/cpp/nlist.c	Thu Apr 12 12:25:27 2012
+++ /sys/src/cmd/cpp/nlist.c	Thu Apr 19 11:44:22 2012
@@ -170,7 +170,7 @@
 			dp[len] = '\0';
 		}
 		fp = (char*)newstring((uchar*)argv[0], strlen(argv[0]), 0);
-		if ((fd = open(fp, 0)) <= 0)
+		if ((fd = open(fp, 0)) < 0)
 			error(FATAL, "Can't open input file %s", fp);
 	}
 	if (argc > 1) {