build: add -fPIC and zlib build features

sys/Cargo.toml

@@ -28,6 +28,10 @@ build-license-gpl      = ["build"]
 build-license-nonfree  = ["build"]
 build-license-version3 = ["build"]
 
+# misc
+build-pic  = ["build"]
+build-zlib = ["build"]
+
 # ssl
 build-lib-gnutls  = ["build"]
 build-lib-openssl = ["build"]

sys/build.rs

@@ -203,6 +203,9 @@ fn build() -> io::Result<()> {
 	enable!(configure, "BUILD_LIB_SMBCLIENT", "libsmbclient");
 	enable!(configure, "BUILD_LIB_SSH", "libssh");
 
+	// configure misc build options
+	enable!(configure, "BUILD_PIC", "pic");
+
 	// run ./configure
 	if !try!(configure.status()).success() {
 		return Err(io::Error::new(io::ErrorKind::Other, "configure failed"));
@@ -342,6 +345,10 @@ fn main() {
 	if env::var("CARGO_FEATURE_BUILD").is_ok() {
 		println!("cargo:rustc-link-search=native={}", search().join("lib").to_string_lossy());
 
+		if env::var("CARGO_FEATURE_BUILD_ZLIB").is_ok() && cfg!(target_os = "linux") {
+			println!("cargo:rustc-link-lib=z");
+		}
+
 		if fs::metadata(&search().join("lib").join("libavutil.a")).is_ok() {
 			return;
 		}