Ignore unused_mod.rs file in code coverage results

As discussed in
#92142 (comment),
tests that contain multiple files order their results differently on
Windows and Linux which the test runner currently can't handle
correctly. For now, ignore the "bin" part of the test and only include
the unused library dependency which is what the test really cares about
anyway.

src/test/run-make-fulldeps/coverage-reports/Makefile

@@ -64,7 +64,7 @@ endif
 # if and when we allow `llvm-cov` to produce results for multiple files. Note, the path separators
 # appear to be normalized to `/` in those files, thankfully.)
 LLVM_COV_IGNORE_FILES=\
-	--ignore-filename-regex='(uses_crate.rs|uses_inline_crate.rs)'
+	--ignore-filename-regex='(uses_crate.rs|uses_inline_crate.rs|unused_mod.rs)'
 
 all: $(patsubst $(SOURCEDIR)/lib/%.rs,%,$(wildcard $(SOURCEDIR)/lib/*.rs)) $(patsubst $(SOURCEDIR)/%.rs,%,$(wildcard $(SOURCEDIR)/*.rs))
 

src/test/run-make-fulldeps/coverage-reports/expected_show_coverage.unused_mod.txt

@@ -1,13 +1,4 @@
-../coverage/lib/unused_mod_helper.rs:
     1|      0|pub fn never_called_function() {
     2|      0|    println!("I am never called");
     3|      0|}
 
-../coverage/unused_mod.rs:
-    1|       |#[path = "lib/unused_mod_helper.rs"]
-    2|       |mod unused_module;
-    3|       |
-    4|      1|fn main() {
-    5|      1|    println!("hello world!");
-    6|      1|}
-