Fix test now that we look at the full error-pattern. Also enable it for rustc.

src/Makefile

@@ -511,6 +511,7 @@ TEST_XFAILS_RUSTC := $(filter-out \
                         import4.rs \
                         import-loop.rs \
                         import-loop-2.rs \
+                        multiline-comment-line-tracking.rs \
                         while-type-error.rs \
                         ), \
                       $(wildcard test/*/*.rs test/*/*.rc))

src/test/compile-fail/multiline-comment-line-tracking.rs

@@ -1,5 +1,5 @@
 // -*- rust -*-
-// error-pattern:9:2:E
+// error-pattern:9:2
 
 /* 1
  * 2