Solaris doesn't include a flock function

Disable the flock wrapper and related consts on Solaris, but leave
them in place for OpenSolaris derivatives like Illumos which do have
a BSD-esque flock.

Author: Alex Zepeda

src/unix/mod.rs

@@ -1067,6 +1067,7 @@ extern "C" {
     )]
     pub fn realpath(pathname: *const ::c_char, resolved: *mut ::c_char) -> *mut ::c_char;
 
+    #[cfg(not(target_os = "solaris"))]
     pub fn flock(fd: ::c_int, operation: ::c_int) -> ::c_int;
 
     #[cfg_attr(target_os = "netbsd", link_name = "__times13")]

src/unix/solarish/mod.rs

@@ -1915,10 +1915,16 @@ pub const SHUT_RD: ::c_int = 0;
 pub const SHUT_WR: ::c_int = 1;
 pub const SHUT_RDWR: ::c_int = 2;
 
-pub const LOCK_SH: ::c_int = 1;
-pub const LOCK_EX: ::c_int = 2;
-pub const LOCK_NB: ::c_int = 4;
-pub const LOCK_UN: ::c_int = 8;
+// These don't exist on Solaris, but do on OpenSolaris derivatives
+// e.g. https://illumos.org/man/3C/flock
+cfg_if! {
+    if #[cfg(not(target_os = "solaris"))] {
+        pub const LOCK_SH: ::c_int = 1;
+        pub const LOCK_EX: ::c_int = 2;
+        pub const LOCK_NB: ::c_int = 4;
+        pub const LOCK_UN: ::c_int = 8;
+    }
+}
 
 pub const F_RDLCK: ::c_short = 1;
 pub const F_WRLCK: ::c_short = 2;