Test crate loading error stderr

And remove E0464 from test-exemption list, since it now has a full test.

Author: camelid

src/test/ui/crate-loading/crateresolve1.rs

@@ -1,10 +1,13 @@
-// dont-check-compiler-stderr
 // aux-build:crateresolve1-1.rs
 // aux-build:crateresolve1-2.rs
 // aux-build:crateresolve1-3.rs
-// error-pattern:multiple matching crates for `crateresolve1`
+
+// normalize-stderr-test: "\.nll/" -> "/"
+// normalize-stderr-test: "\\\?\\" -> ""
+// normalize-stderr-test: "libcrateresolve1-([123])\.[a-z]+" -> "libcrateresolve1-$1.somelib"
 
 extern crate crateresolve1;
+//~^ ERROR multiple matching crates for `crateresolve1`
 
 fn main() {
 }

src/test/ui/crate-loading/crateresolve1.stderr

@@ -0,0 +1,13 @@
+error[E0464]: multiple matching crates for `crateresolve1`
+  --> $DIR/crateresolve1.rs:9:1
+   |
+LL | extern crate crateresolve1;
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: candidates:
+           crate `crateresolve1`: $TEST_BUILD_DIR/crate-loading/crateresolve1/auxiliary/libcrateresolve1-1.somelib
+           crate `crateresolve1`: $TEST_BUILD_DIR/crate-loading/crateresolve1/auxiliary/libcrateresolve1-2.somelib
+           crate `crateresolve1`: $TEST_BUILD_DIR/crate-loading/crateresolve1/auxiliary/libcrateresolve1-3.somelib
+
+error: aborting due to previous error
+

src/tools/tidy/src/error_codes_check.rs

@@ -10,8 +10,8 @@ use regex::Regex;
 
 // A few of those error codes can't be tested but all the others can and *should* be tested!
 const EXEMPTED_FROM_TEST: &[&str] = &[
-    "E0227", "E0279", "E0280", "E0313", "E0377", "E0461", "E0462", "E0464", "E0465", "E0476",
-    "E0514", "E0519", "E0523", "E0554", "E0640", "E0717", "E0729",
+    "E0227", "E0279", "E0280", "E0313", "E0377", "E0461", "E0462", "E0465", "E0476", "E0514",
+    "E0519", "E0523", "E0554", "E0640", "E0717", "E0729",
 ];
 
 // Some error codes don't have any tests apparently...