Signal controlling constants for windows

SIG_DFL and similar.

Closes #1600.

Author: vorner

libc-test/build.rs

@@ -583,7 +583,9 @@ fn test_windows(target: &str) {
         match name {
             // FIXME: API error:
             // SIG_ERR type is "void (*)(int)", not "int"
-            "SIG_ERR" => true,
+            "SIG_ERR" |
+            // Similar for SIG_DFL/IGN/GET/SGE/ACK
+            "SIG_DFL" | "SIG_IGN" | "SIG_GET" | "SIG_SGE" | "SIG_ACK" => true,
             // FIXME: newer windows-gnu environment on CI?
             "_O_OBTAIN_DIR" if gnu => true,
             _ => false,

libc-test/semver/windows.txt

@@ -123,7 +123,12 @@ SIGILL
 SIGINT
 SIGSEGV
 SIGTERM
+SIG_ACK
+SIG_DFL
 SIG_ERR
+SIG_GET
+SIG_IGN
+SIG_SGE
 SOCKET
 STRUNCATE
 S_IEXEC

src/windows/mod.rs

@@ -244,7 +244,13 @@ pub const SIGSEGV: ::c_int = 11;
 pub const SIGTERM: ::c_int = 15;
 pub const SIGABRT: ::c_int = 22;
 pub const NSIG: ::c_int = 23;
+
 pub const SIG_ERR: ::c_int = -1;
+pub const SIG_DFL: ::sighandler_t = 0;
+pub const SIG_IGN: ::sighandler_t = 1;
+pub const SIG_GET: ::sighandler_t = 2;
+pub const SIG_SGE: ::sighandler_t = 3;
+pub const SIG_ACK: ::sighandler_t = 4;
 
 // inline comment below appeases style checker
 #[cfg(all(target_env = "msvc", feature = "rustc-dep-of-std"))] // " if "