Remove left-over from some logging plan making complete syscalls atomic

0 is not a system call (thanks to Peter Froehlich)

syscall.c

@@ -129,9 +129,7 @@ syscall(void)
   int num;
 
   num = proc->tf->eax;
-  if(num >= 0 && num < SYS_open && syscalls[num]) {
-    proc->tf->eax = syscalls[num]();
-  } else if (num >= SYS_open && num < NELEM(syscalls) && syscalls[num]) {
+  if(num > 0 && num < NELEM(syscalls) && syscalls[num]) {
     proc->tf->eax = syscalls[num]();
   } else {
     cprintf("%d %s: unknown sys call %d\n",

syscall.h

@@ -13,7 +13,6 @@
 #define SYS_sbrk   12
 #define SYS_sleep  13
 #define SYS_uptime 14
-
 #define SYS_open   15
 #define SYS_write  16
 #define SYS_mknod  17