support to link system dylib

Cargo.toml

@@ -22,8 +22,9 @@ edition = "2021"
 opt-level = 2
 
 [build-dependencies]
-cc = "1.1"
-glob = "0.3.1"
+cc = "1"
+glob = "0.3"
+pkg-config = "0.3.27"
 
 [features]
 default = ["std", "parallel"]
@@ -32,3 +33,4 @@ parallel = ["cc/parallel"]
 neon = []                      # ARM NEON SIMD (will crash on ARM CPUs without it)
 sse41 = []                     # x64 SSE 4.1 (will crash on x86 CPUs without it)
 avx2 = []                      # x64 AVX2 (will crash on x86 CPUs without it)
+system-dylib = []                     # Use the system-installed dylib instead of compiling a static library from the vendor

build.rs

@@ -1,10 +1,17 @@
-extern crate cc;
-extern crate glob;
-
 use std::env;
 use std::path::PathBuf;
 
 fn main() {
+    if cfg!(feature = "system-link") {
+        let lib_name = "libwebp";
+        let find_system_lib = pkg_config::Config::new().probe(lib_name).is_ok();
+
+        if find_system_lib {
+            println!("cargo:rustc-link-lib={}", lib_name);
+            return;
+        }
+    }
+
     let manifest_dir =
         PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR"));
     let vendor = manifest_dir.join("vendor");