Corrently null-terminate the path being passed to the opendir() calls,

malloc() does is not defined to return a zeroed buffer leading to
"strange" problems.

Submitted by: Karl Denninger <karl@mcs.com>, PR#1826

lib/libc/gen/getcwd.c

@@ -154,6 +154,7 @@ getcwd(pt, size)
 
 		/* Add trailing slash for next directory. */
 		*bup++ = '/';
+		*bup = '\0';
 
 		/*
 		 * If it's a mount point, have to stat each element because