Bring back SYS_pkey_* for musl

Author: oxalica

src/unix/linux_like/linux/musl/b32/x86/mod.rs

@@ -914,8 +914,9 @@ pub const SYS_mlock2: ::c_long = 376;
 pub const SYS_copy_file_range: ::c_long = 377;
 pub const SYS_preadv2: ::c_long = 378;
 pub const SYS_pwritev2: ::c_long = 379;
-// FIXME syscalls 380-382 have been added in musl 1.16
-// See discussion https://github.com/rust-lang/libc/pull/699
+pub const SYS_pkey_mprotect: ::c_long = 380;
+pub const SYS_pkey_alloc: ::c_long = 381;
+pub const SYS_pkey_free: ::c_long = 382;
 pub const SYS_statx: ::c_long = 383;
 
 // offsets in user_regs_structs, from sys/reg.h

src/unix/linux_like/linux/musl/b64/x86_64/mod.rs

@@ -576,8 +576,9 @@ pub const SYS_mlock2: ::c_long = 325;
 pub const SYS_copy_file_range: ::c_long = 326;
 pub const SYS_preadv2: ::c_long = 327;
 pub const SYS_pwritev2: ::c_long = 328;
-// FIXME syscalls 329-331 have been added in musl 1.16
-// See discussion https://github.com/rust-lang/libc/pull/699
+pub const SYS_pkey_mprotect: ::c_long = 329;
+pub const SYS_pkey_alloc: ::c_long = 330;
+pub const SYS_pkey_free: ::c_long = 331;
 pub const SYS_statx: ::c_long = 332;
 
 // offsets in user_regs_structs, from sys/reg.h