Use pkg-config for all linked libraries.

Fixes crashes when mixing wide and non-wide linker dependencies.

For example if both the "wide" and the "panel" features are enabled,
libncursesw.so and libpanel.so were linked which can not work together.

Another example is on Gentoo Linux where ncurses is split into
libncurses.so and libtinfo.so, previously libtinfo.so and libncursesw.so
were linked together if the "wide" feature was set.

Also fix the recognition of wide_chtype for non-default include paths.

Fixes #151.

build.rs

@@ -1,17 +1,52 @@
 extern crate gcc;
 extern crate pkg_config;
 
+use pkg_config::Library;
 use std::env;
 use std::fs::File;
 use std::io::Write;
 use std::path::Path;
 use std::process::Command;
 
+fn find_library(names: &[&str]) -> Option<Library> {
+    for name in names {
+        if let Ok(lib) = pkg_config::probe_library(name) {
+            return Some(lib);
+        }
+    }
+    println!("cargo:rustc-link-lib={}", names.last().unwrap());
+    None
+}
+
 fn main() {
-    check_chtype_size();
+    let wide = cfg!(all(feature = "wide", not(target_os = "macos")));
+
+    let ncurses_lib = if wide {
+        find_library(&["ncursesw5", "ncursesw"])
+    } else {
+        find_library(&["ncurses5", "ncurses"])
+    };
+
+    if cfg!(feature = "menu") {
+        if wide {
+            find_library(&["menuw5", "menuw"]);
+        } else {
+            find_library(&["menu5", "menu"]);
+        }
+    }
+
+    if cfg!(feature = "panel") {
+        if wide {
+            find_library(&["panelw5", "panelw"]);
+        } else {
+            find_library(&["panel5", "panel"]);
+        }
+    }
+
+    check_chtype_size(&ncurses_lib);
 }
 
-fn check_chtype_size() {
+fn check_chtype_size(ncurses_lib: &Option<Library>) {
     let out_dir = env::var("OUT_DIR").expect("cannot get OUT_DIR");
     let src = format!("{}", Path::new(&out_dir).join("chtype_size.c").display());
     let bin = format!("{}", Path::new(&out_dir).join("chtype_size").display());
@@ -36,22 +71,20 @@ int main(void)
 }
     ").expect(&format!("cannot write into {}", src));
 
-    let cfg = gcc::Config::new();
-    let compiler = cfg.get_compiler();
+    let compiler = gcc::Build::new().get_compiler();
 
-    Command::new(compiler.path()).arg(&src).arg("-o").arg(&bin)
-                                 .status().expect("compilation failed");
+    let mut compile_cmd = Command::new(compiler.path());
+    compile_cmd.arg(&src).arg("-o").arg(&bin);
+    if let Some(lib) = ncurses_lib {
+        for path in lib.include_paths.iter() {
+            compile_cmd.arg("-I").arg(path);
+        }
+    }
+    compile_cmd.status().expect("compilation failed");
     let features = Command::new(&bin).output()
                    .expect(&format!("{} failed", bin));
     print!("{}", String::from_utf8_lossy(&features.stdout));
 
-    let ncurses_names = ["ncurses5", "ncurses"];
-    for ncurses_name in &ncurses_names {
-        if pkg_config::probe_library(ncurses_name).is_ok() {
-            break;
-        }
-    }
-
     std::fs::remove_file(&src).expect(&format!("cannot delete {}", src));
     std::fs::remove_file(&bin).expect(&format!("cannot delete {}", bin));
 }