refactor: annotate ELAST constants as unstable

this patch annotates symbols that are known to have been the source of
semver-breaking issues by using a macro for which another pr has been
opened. these issues have been tracked thus far in #3131.

Author: dybucc

src/unix/bsd/apple/mod.rs

@@ -2143,6 +2143,9 @@ pub const ENOTRECOVERABLE: c_int = 104;
 pub const EOWNERDEAD: c_int = 105;
 pub const EQFULL: c_int = 106;
 pub const ENOTCAPABLE: c_int = 107;
+
+/// This symbols is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const ELAST: c_int = 107;
 
 pub const EAI_AGAIN: c_int = 2;

src/unix/bsd/freebsdlike/dragonfly/mod.rs

@@ -548,7 +548,11 @@ pub const ENOMEDIUM: c_int = 93;
 pub const ENOTRECOVERABLE: c_int = 94;
 pub const EOWNERDEAD: c_int = 95;
 pub const EASYNC: c_int = 99;
+
+/// This symbols is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const ELAST: c_int = 99;
+
 pub const RLIMIT_POSIXLOCKS: c_int = 11;
 #[deprecated(since = "0.2.64", note = "Not stable across OS versions")]
 pub const RLIM_NLIMITS: crate::rlim_t = 12;

src/unix/bsd/freebsdlike/freebsd/freebsd11/mod.rs

@@ -258,7 +258,10 @@ s! {
     }
 }
 
+/// This symbols is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const ELAST: c_int = 96;
+
 pub const RAND_MAX: c_int = 0x7fff_fffd;
 pub const KI_NSPARE_PTR: usize = 6;
 pub const MINCORE_SUPER: c_int = 0x20;

src/unix/bsd/freebsdlike/freebsd/freebsd12/mod.rs

@@ -304,6 +304,9 @@ s! {
 }
 
 pub const RAND_MAX: c_int = 0x7fff_fffd;
+
+/// This symbols is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const ELAST: c_int = 97;
 
 /// max length of devicename

src/unix/bsd/freebsdlike/freebsd/freebsd13/mod.rs

@@ -317,6 +317,9 @@ s! {
 }
 
 pub const RAND_MAX: c_int = 0x7fff_ffff;
+
+/// This symbols is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const ELAST: c_int = 97;
 
 pub const KF_TYPE_EVENTFD: c_int = 13;

src/unix/bsd/freebsdlike/freebsd/freebsd14/mod.rs

@@ -319,6 +319,9 @@ s! {
 }
 
 pub const RAND_MAX: c_int = 0x7fff_ffff;
+
+/// This symbols is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const ELAST: c_int = 97;
 
 pub const KF_TYPE_EVENTFD: c_int = 13;

src/unix/bsd/freebsdlike/freebsd/freebsd15/mod.rs

@@ -321,6 +321,9 @@ s! {
 }
 
 pub const RAND_MAX: c_int = 0x7fff_ffff;
+
+/// This symbols is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const ELAST: c_int = 97;
 
 pub const KF_TYPE_EVENTFD: c_int = 13;

src/unix/bsd/netbsdlike/openbsd/mod.rs

@@ -945,6 +945,9 @@ pub const EBADMSG: c_int = 92;
 pub const ENOTRECOVERABLE: c_int = 93;
 pub const EOWNERDEAD: c_int = 94;
 pub const EPROTO: c_int = 95;
+
+/// This symbols is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const ELAST: c_int = 95;
 
 pub const F_DUPFD_CLOEXEC: c_int = 10;