Add more fcntl and seal constants for Android/Linux

A new binary is generated for testing this, but it's not yet been
connected to CI. It can be run locally, however, via `cargo run
--bin linux_fcntl` within the libc-test folder.

libc-test/build.rs

@@ -459,6 +459,11 @@ fn main() {
             // asm/termios.h and ioctl.h (+ some other headers) because of redeclared types.
             "CMSPAR" if mips && linux && !musl => true,
 
+            // These constants are tested in a separate test program generated below because there
+            // are header conflicts if we try to include the headers that define them here.
+            "F_CANCELLK" | "F_ADD_SEALS" | "F_GET_SEALS" => true,
+            "F_SEAL_SEAL" | "F_SEAL_SHRINK" | "F_SEAL_GROW" | "F_SEAL_WRITE" => true,
+
             _ => false,
         }
     });
@@ -635,4 +640,23 @@ fn main() {
     } else {
         cfg.generate("../src/lib.rs", "all.rs");
     }
+
+    // On Linux or Android also generate another script for testing linux/fcntl declarations.
+    // These cannot be tested normally because including both `linux/fcntl.h` and `fcntl.h`
+    // fails on a lot of platforms.
+    if android || linux {
+        let mut cfg = ctest::TestGenerator::new();
+        cfg.header("linux/fcntl.h");
+        cfg.skip_type(|_| true)
+           .skip_struct(|_| true)
+           .skip_fn(|_| true);
+        cfg.skip_const(move |name| {
+            match name {
+                "F_CANCELLK" | "F_ADD_SEALS" | "F_GET_SEALS" => false,
+                "F_SEAL_SEAL" | "F_SEAL_SHRINK" | "F_SEAL_GROW" | "F_SEAL_WRITE" => false,
+                _ => true,
+            }
+        });
+        cfg.generate("../src/lib.rs", "linux_fcntl.rs");
+    }
 }

src/unix/notbsd/mod.rs

@@ -212,9 +212,17 @@ pub const F_SETFL: ::c_int = 4;
 pub const F_SETLEASE: ::c_int = 1024;
 pub const F_GETLEASE: ::c_int = 1025;
 pub const F_NOTIFY: ::c_int = 1026;
+pub const F_CANCELLK: ::c_int = 1029;
 pub const F_DUPFD_CLOEXEC: ::c_int = 1030;
 pub const F_SETPIPE_SZ: ::c_int = 1031;
 pub const F_GETPIPE_SZ: ::c_int = 1032;
+pub const F_ADD_SEALS: ::c_int = 1033;
+pub const F_GET_SEALS: ::c_int = 1034;
+
+pub const F_SEAL_SEAL: ::c_int = 0x0001;
+pub const F_SEAL_SHRINK: ::c_int = 0x0002;
+pub const F_SEAL_GROW: ::c_int = 0x0004;
+pub const F_SEAL_WRITE: ::c_int = 0x0008;
 
 // TODO(#235): Include file sealing fcntls once we have a way to verify them.