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.

cranelift/src/cton-util.rs

@@ -38,12 +38,12 @@ Options:
     -T, --time-passes
                     print pass timing report
     -t, --just-decode
-                    just decode WebAssembly to Cretonne IL
+                    just decode WebAssembly to Cretonne IR
     -s, --print-size
                     prints generated code size
     -c, --check-translation
-                    just checks the correctness of Cretonne IL translated from WebAssembly
-    -p, --print     print the resulting Cretonne IL
+                    just checks the correctness of Cretonne IR translated from WebAssembly
+    -p, --print     print the resulting Cretonne IR
     -h, --help      print this help message
     --set=<set>     configure Cretonne settings
     --isa=<isa>     specify the Cretonne ISA