make syscall.h consistent with linux

make syscall.h consistent with linux

most of the found naming differences don't matter to musl, because
internally it unifies the syscall names that vary across targets,
but for external code the names should match the kernel uapi.

aarch64:
	__NR_fstatat is called __NR_newfstatat in linux.
	__NR_or1k_atomic got mistakenly copied from or1k.
arm:
	__NR_arm_sync_file_range is an alias for __NR_sync_file_range2
	__NR_fadvise64_64 is called __NR_arm_fadvise64_64 in linux,
	the old non-arm name is kept too, it should not cause issues.
	(powerpc has similar nonstandard fadvise and it uses the
	normal name.)
i386:
	__NR_madvise1 was removed from linux in commit
	303395ac3bf3e2cb488435537d416bc840438fcb 2011-11-11
microblaze:
	__NR_fadvise, __NR_fstatat, __NR_pread, __NR_pwrite
	had different name in linux.
mips:
	__NR_fadvise, __NR_fstatat, __NR_pread, __NR_pwrite, __NR_select
	had different name in linux.
mipsn32:
	__NR_fstatat is called __NR_newfstatat in linux.
or1k:
	__NR__llseek is called __NR_llseek in linux.
	the old name is kept too because that's the name musl uses
	internally.
powerpc:
	__NR_{get,set}res{gid,uid}32 was never present in powerpc linux.
	__NR_timerfd was briefly defined in linux but then got renamed.