Auto merge of #2814 - lattice0:feature-android-sys-prctl.h, r=JohnTitor

adds android sys/prctl.h

adds some sys/prctl.h symbols to Android, checked against the NDK .h file for validity of numbers.

These are needed for making [firecracker](https://github.com/firecracker-microvm/firecracker/blob/6b4a4b1c0490e006e02db7579831cbf14e05abae/src/seccompiler/src/backend.rs#L943) work on Android hosts

Author: bors

libc-test/semver/android.txt

@@ -1638,6 +1638,10 @@ POSIX_FADV_SEQUENTIAL
 POSIX_FADV_WILLNEED
 PR_SET_VMA
 PR_SET_VMA_ANON_NAME
+PR_SET_NO_NEW_PRIVS
+PR_GET_NO_NEW_PRIVS
+PR_GET_SECCOMP
+PR_SET_SECCOMP
 PRIO_MAX
 PRIO_MIN
 PRIO_PGRP

src/unix/linux_like/android/mod.rs

@@ -2498,6 +2498,10 @@ pub const PROP_NAME_MAX: ::c_int = 32;
 // sys/prctl.h
 pub const PR_SET_VMA: ::c_int = 0x53564d41;
 pub const PR_SET_VMA_ANON_NAME: ::c_int = 0;
+pub const PR_SET_NO_NEW_PRIVS: ::c_int = 38;
+pub const PR_GET_NO_NEW_PRIVS: ::c_int = 39;
+pub const PR_GET_SECCOMP: ::c_int = 21;
+pub const PR_SET_SECCOMP: ::c_int = 22;
 
 f! {
     pub fn CMSG_NXTHDR(mhdr: *const msghdr,