disable generation of lttng tracepoints if no tracing feature set

Signed-off-by: Fabrizio <fab@pop-os.localdomain>

build.rs

@@ -1,9 +1,11 @@
 use std::env;
 use std::path::PathBuf;
 
+#[cfg(feature = "tracing")]
 use lttng_ust_generate::{Provider, Generator, CTFType, CIntegerType};
 
-fn main() {
+#[cfg(feature = "tracing")]
+fn setup_tracepoints() {
     // the provider is called calendar
     let mut provider = Provider::new("calendar");
 
@@ -23,3 +25,8 @@ fn main() {
         .generate()
         .expect("Unable to generate tracepoint bindings");
 }
+
+fn main() {
+    #[cfg(feature = "tracing")]
+    setup_tracepoints();
+}