Say "IR" instead of "IL".

While the specifics of these terms are debatable, "IR" generally
isn't incorrect in this context, and is the more widely recognized
term at this time.

See also the discussion in #267.

Fixes #267.

lib/cretonne/src/timing.rs

@@ -41,11 +41,11 @@ define_passes!{
     Pass, NUM_PASSES, DESCRIPTIONS;
 
     process_file: "Processing test file",
-    parse_text: "Parsing textual Cretonne IL",
+    parse_text: "Parsing textual Cretonne IR",
     wasm_translate_module: "Translate WASM module",
     wasm_translate_function: "Translate WASM function",
 
-    verifier: "Verify Cretonne IL",
+    verifier: "Verify Cretonne IR",
     verify_cssa: "Verify CSSA",
     verify_liveness: "Verify live ranges",
     verify_locations: "Verify value locations",