reenable sync_file_range; should no longer break on mips

src/linux/sync_file_range.c

@@ -5,10 +5,10 @@
 
 int sync_file_range(int fd, off_t pos, off_t len, unsigned flags)
 {
-#if 0 && defined(SYS_sync_file_range2)
+#if defined(SYS_sync_file_range2)
 	return syscall(SYS_sync_file_range2, fd, flags,
 		__SYSCALL_LL_E(pos), __SYSCALL_LL_E(len));
-#elif 0 && defined(SYS_sync_file_range)
+#elif defined(SYS_sync_file_range)
 	return syscall(SYS_sync_file_range, fd,
 		__SYSCALL_LL_O(pos), __SYSCALL_LL_E(len), flags);
 #else