Split crate into shared logic library and binary crate (#52)

crates/shared/build.rs

@@ -0,0 +1,17 @@
+use vergen_gitcl::{Emitter, GitclBuilder};
+
+fn main() {
+    let gitcl = GitclBuilder::default()
+        .branch(true)
+        .sha(true)
+        .build()
+        .unwrap();
+    Emitter::default()
+        .add_instructions(&gitcl)
+        .unwrap()
+        .emit()
+        .unwrap();
+
+    #[cfg(target_os = "linux")]
+    println!("cargo:rustc-link-arg=-Wl,-rpath,$ORIGIN");
+}