fix bug from syscall overhaul: extra __syscall_ret call for 0-arg syscalls

this mainly just caused bloat, but could corrupt errno if a 0-arg
syscall ever failed.

arch/i386/bits/syscall.h

@@ -6,7 +6,7 @@ static inline long __syscall0(long __n)
 {
 	unsigned long __ret;
 	__asm__ __volatile__ ("int $128" : "=a"(__ret) : "a"(__n) : "memory");
-	return __syscall_ret(__ret);
+	return __ret;
 }
 
 #ifndef __PIC__