Add klogctl to linux and android

For android, we also add the `KLOG_*` constants. For linux, they are
defined in source but not exported to user space.

(backport <rust-lang#3777>)
(cherry picked from commit ece907b)

Author: sgasse

src/unix/linux_like/android/mod.rs

@@ -3526,6 +3526,18 @@ pub const AT_RSEQ_ALIGN: c_ulong = 28;
 pub const AT_EXECFN: c_ulong = 31;
 pub const AT_MINSIGSTKSZ: c_ulong = 51;
 
+pub const KLOG_CLOSE: ::c_int = 0;
+pub const KLOG_OPEN: ::c_int = 1;
+pub const KLOG_READ: ::c_int = 2;
+pub const KLOG_READ_ALL: ::c_int = 3;
+pub const KLOG_READ_CLEAR: ::c_int = 4;
+pub const KLOG_CLEAR: ::c_int = 5;
+pub const KLOG_CONSOLE_OFF: ::c_int = 6;
+pub const KLOG_CONSOLE_ON: ::c_int = 7;
+pub const KLOG_CONSOLE_LEVEL: ::c_int = 8;
+pub const KLOG_SIZE_UNREAD: ::c_int = 9;
+pub const KLOG_SIZE_BUFFER: ::c_int = 10;
+
 // Most `*_SUPER_MAGIC` constants are defined at the `linux_like` level; the
 // following are only available on newer Linux versions than the versions
 // currently used in CI in some configurations, so we define them here.