deal with the fact that the definition of oseek and _nsec aren't in libc.h

Reference: /n/atom/patch/applied/syscall_nsec
Date: Wed Apr 22 04:49:03 CES 2015
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/syscall/syscall.c	Wed Apr 22 04:48:54 2015
+++ /sys/src/cmd/syscall/syscall.c	Wed Apr 22 04:48:55 2015
@@ -26,8 +26,8 @@
 int	_fsession(char*, void*, int);
 int	_mount(int, char*, int, char*);
 int	_wait(void*);
-long	oseek(int, long, int);
 vlong	_nsec(void);
+long	oseek(int, long, int);
 
 struct{
 	char	*name;
@@ -122,8 +122,8 @@
 				r=pread(arg[0], (void*)arg[1], arg[2], strtoll(argv[4], 0, 0));
 			else if(strcmp(argv[0], "pwrite") == 0)
 				r=pwrite(arg[0], (void*)arg[1], arg[2], strtoll(argv[4], 0, 0));
-			else if(strcmp(argv[0], "nsec") == 0 || strcmp(argv[0], "_nsec") == 0)
-				r=_nsec();
+			else if(strcmp(argv[0], "_nsec") == 0)
+				r=nsec();
 			else
 				r=(*tab[i].func)(arg[0], arg[1], arg[2], arg[3], arg[4]);
 			if(r == -1){