update syscalls with off_t arguments to handle argument alignment, if needed

the arm syscall abi requires 64-bit arguments to be aligned on an even
register boundary. these new macros facilitate meeting the abi
requirement without imposing significant ugliness on the code.

arch/arm/bits/syscall.h

@@ -1,6 +1,7 @@
-#define __SYSCALL_LL(x) \
+#define __SYSCALL_LL_E(x) \
 ((union { long long ll; long l[2]; }){ .ll = x }).l[0], \
 ((union { long long ll; long l[2]; }){ .ll = x }).l[1]
+#define __SYSCALL_LL_O(x) 0, __SYSCALL_LL_E((x))
 
 long (__syscall)(long, ...);