Added flac and mp3 output format.

build.rs

@@ -0,0 +1,25 @@
+/*
+ * Build script for tuxrecord2.
+ *
+ * The FLAC and MP3 encoders are provided by the system libFLAC and
+ * libmp3lame libraries, which are used through the small FFI shims in
+ * src/flac.rs and src/mp3.rs. Locate them with pkg-config (which also
+ * emits the correct link flags and library search paths) so builds work
+ * on distributions where the headers/libraries live in non-standard
+ * locations.
+ */
+
+fn main() {
+    for lib in ["flac", "lame"] {
+        pkg_config::Config::new().probe(lib).unwrap_or_else(|err| {
+            panic!(
+                "could not find the '{lib}' library with pkg-config: {err}\n\
+                     Install the development package (e.g. 'libflac-dev' and \
+                     'libmp3lame-dev' on Debian/Ubuntu, 'flac-devel' and \
+                     'lame-devel' on Fedora, 'flac' and 'lame' on Arch)."
+            );
+        });
+    }
+
+    println!("cargo:rerun-if-changed=build.rs");
+}