[llvm-cov] Implement -ignore-filename-regex= option for excluding source files.

Summary:
The option is helpful for large projects where it's not feasible to specify sources which
user would like to see in the report. Instead, it allows to black-list specific sources via
regular expressions (e.g. now it's possible to skip all files that have "test" in its name).

This also partially fixes https://bugs.llvm.org/show_bug.cgi?id=34277

Reviewers: vsk, morehouse, liaoyuke

Reviewed By: vsk

Subscribers: kcc, mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D43907

llvm-svn: 329581
diff --git a/llvm/tools/llvm-cov/CoverageReport.h b/llvm/tools/llvm-cov/CoverageReport.h
index f90729b..8864d30 100644
--- a/llvm/tools/llvm-cov/CoverageReport.h
+++ b/llvm/tools/llvm-cov/CoverageReport.h
@@ -53,7 +53,8 @@
                           const CoverageFilter *Filters);
 
   /// Render file reports for every unique file in the coverage mapping.
-  void renderFileReports(raw_ostream &OS) const;
+  void renderFileReports(raw_ostream &OS,
+                         const CoverageFilters &IgnoreFilenameFilters) const;
 
   /// Render file reports for the files specified in \p Files.
   void renderFileReports(raw_ostream &OS, ArrayRef<std::string> Files) const;