add dlopen Cargo feature using dlib to load fontconfig at runtime

Fixes yeslogic#11

.travis.yml

@@ -13,7 +13,7 @@ rust:
   - nightly
   - beta
   - stable
-  - 1.38.0
+  - 1.40.0
 
 jobs:
   allow_failures:

fontconfig-sys/Cargo.toml

@@ -1,6 +1,7 @@
 [package]
 name = "yeslogic-fontconfig-sys"
 version = "2.11.2"
+edition = "2018"
 authors = [
     "Austin Bonander <[email protected]>",
     "The Servo Project Developers",
@@ -16,7 +17,6 @@ homepage = "https://github.com/yeslogic/fontconfig-rs"
 documentation = "https://docs.rs/crate/yeslogic-fontconfig-sys"
 repository = "https://github.com/yeslogic/fontconfig-rs"
 
-build = "build.rs"
 links = "fontconfig"
 
 [badges]
@@ -27,6 +27,11 @@ name = "fontconfig_sys"
 
 [dependencies]
 const-cstr = "0.3"
+dlib = "0.5.0"
+lazy_static = { verison = "1.4.0", optional = true }
+
+[features]
+dlopen = [ "lazy_static" ]
 
 [build-dependencies]
 pkg-config = "0.3"

fontconfig-sys/build.rs

@@ -1,5 +1,6 @@
 extern crate pkg_config;
 
 fn main() {
+    #[cfg(not(feature = "dlopen"))]
     pkg_config::find_library("fontconfig").unwrap();
 }