Auto merge of #2172 - tarcieri:musl-hwcaps, r=Amanieu

musl: add missing AArch64 HWCAP_* consts

Closes #2171.

I effectively just copied and pasted these from #1638 after confirming that they are identical to musl's [aarch64/bits/hwcap.h](https://github.com/bminor/musl/blob/4433115/arch/aarch64/bits/hwcap.h) and that musl's `getauxval()` also takes a `c_ulong`.

It seems like if these are added it would address some of [`TODO-linux.txt`](https://github.com/rust-lang/libc/blob/ed1399a/libc-test/semver/TODO-linux.txt)?

libc-test/semver/TODO-linux.txt

@@ -1,38 +1,6 @@
 # The following symbols are not not available in some combinations of
 # musl/gnu/android and/or architecture.
 BOTHER
-HWCAP_AES
-HWCAP_ASIMD
-HWCAP_ASIMDDP
-HWCAP_ASIMDFHM
-HWCAP_ASIMDHP
-HWCAP_ASIMDRDM
-HWCAP_ATOMICS
-HWCAP_CPUID
-HWCAP_CRC32
-HWCAP_DCPOP
-HWCAP_DIT
-HWCAP_EVTSTRM
-HWCAP_FCMA
-HWCAP_FLAGM
-HWCAP_FP
-HWCAP_FPHP
-HWCAP_ILRCPC
-HWCAP_JSCVT
-HWCAP_LRCPC
-HWCAP_PACA
-HWCAP_PACG
-HWCAP_PMULL
-HWCAP_SB
-HWCAP_SHA1
-HWCAP_SHA2
-HWCAP_SHA3
-HWCAP_SHA512
-HWCAP_SM3
-HWCAP_SM4
-HWCAP_SSBS
-HWCAP_SVE
-HWCAP_USCAT
 KEYCTL_CAPABILITIES
 KEYCTL_CAPS0_BIG_KEY
 KEYCTL_CAPS0_CAPABILITIES

src/unix/linux_like/linux/musl/b64/aarch64/mod.rs

@@ -160,6 +160,40 @@ pub const ENOTRECOVERABLE: ::c_int = 131;
 pub const ERFKILL: ::c_int = 132;
 pub const EHWPOISON: ::c_int = 133;
 
+// bits/hwcap.h
+pub const HWCAP_FP: ::c_ulong = 1 << 0;
+pub const HWCAP_ASIMD: ::c_ulong = 1 << 1;
+pub const HWCAP_EVTSTRM: ::c_ulong = 1 << 2;
+pub const HWCAP_AES: ::c_ulong = 1 << 3;
+pub const HWCAP_PMULL: ::c_ulong = 1 << 4;
+pub const HWCAP_SHA1: ::c_ulong = 1 << 5;
+pub const HWCAP_SHA2: ::c_ulong = 1 << 6;
+pub const HWCAP_CRC32: ::c_ulong = 1 << 7;
+pub const HWCAP_ATOMICS: ::c_ulong = 1 << 8;
+pub const HWCAP_FPHP: ::c_ulong = 1 << 9;
+pub const HWCAP_ASIMDHP: ::c_ulong = 1 << 10;
+pub const HWCAP_CPUID: ::c_ulong = 1 << 11;
+pub const HWCAP_ASIMDRDM: ::c_ulong = 1 << 12;
+pub const HWCAP_JSCVT: ::c_ulong = 1 << 13;
+pub const HWCAP_FCMA: ::c_ulong = 1 << 14;
+pub const HWCAP_LRCPC: ::c_ulong = 1 << 15;
+pub const HWCAP_DCPOP: ::c_ulong = 1 << 16;
+pub const HWCAP_SHA3: ::c_ulong = 1 << 17;
+pub const HWCAP_SM3: ::c_ulong = 1 << 18;
+pub const HWCAP_SM4: ::c_ulong = 1 << 19;
+pub const HWCAP_ASIMDDP: ::c_ulong = 1 << 20;
+pub const HWCAP_SHA512: ::c_ulong = 1 << 21;
+pub const HWCAP_SVE: ::c_ulong = 1 << 22;
+pub const HWCAP_ASIMDFHM: ::c_ulong = 1 << 23;
+pub const HWCAP_DIT: ::c_ulong = 1 << 24;
+pub const HWCAP_USCAT: ::c_ulong = 1 << 25;
+pub const HWCAP_ILRCPC: ::c_ulong = 1 << 26;
+pub const HWCAP_FLAGM: ::c_ulong = 1 << 27;
+pub const HWCAP_SSBS: ::c_ulong = 1 << 28;
+pub const HWCAP_SB: ::c_ulong = 1 << 29;
+pub const HWCAP_PACA: ::c_ulong = 1 << 30;
+pub const HWCAP_PACG: ::c_ulong = 1 << 31;
+
 pub const MAP_ANON: ::c_int = 0x0020;
 pub const MAP_GROWSDOWN: ::c_int = 0x0100;
 pub const MAP_DENYWRITE: ::c_int = 0x0800;