Carry over PR #134 enhancements for mingw64, thank you @netoffice-zz

Author: dginev

Cargo.toml

@@ -20,9 +20,12 @@ name = "libxml"
 [dependencies]
 libc = "0.2"
 
-[target.'cfg(windows)'.build-dependencies]
+[target.'cfg(all(target_family = "windows", target_env = "msvc"))'.build-dependencies]
 vcpkg = "0.2"
 
+[target.'cfg(all(target_family = "windows", target_env = "gnu"))'.build-dependencies]
+pkg-config = "0.3.2"
+
 [target.'cfg(macos)'.build-dependencies]
 pkg-config = "0.3.2"
 

README.md

@@ -44,6 +44,8 @@ $ pkg install libxml2 pkgconf
 
 ### Windows
 
+#### msvc
+
 [Community contributed](https://github.com/KWARC/rust-libxml/issues/81#issuecomment-760364976):
 
 * manually install builds tools c++ and english language by visiting [BuildTools](https://visualstudio.microsoft.com/fr/thank-you-downloading-visual-studio/?sku=BuildTools&rel=16)
@@ -56,3 +58,7 @@ C:\> refreshenv
 C:\> vcpkg install libxml2:x64-windows
 C:\> vcpkg integrate install
 ```
+
+#### gnu
+
+On mingw64 environment you could install libxml2 with `pacman -S mingw64/mingw-w64-x86_64-libxml2`.

build.rs

@@ -40,7 +40,7 @@ fn find_libxml2() -> Option<ProbedLib> {
     );
     None
   } else {
-    #[cfg(any(target_family = "unix", target_os = "macos"))]
+    #[cfg(any(target_family = "unix", target_os = "macos", all(target_family="windows", target_env="gnu")))]
     {
       let lib = pkg_config::Config::new()
         .probe("libxml-2.0")
@@ -109,7 +109,7 @@ fn main() {
   }
 }
 
-#[cfg(target_family = "windows")]
+#[cfg(all(target_family = "windows", target_env = "msvc"))]
 mod vcpkg_dep {
   use crate::ProbedLib;
   pub fn vcpkg_find_libxml2() -> Option<ProbedLib> {