Subject: Update .gitignore from Debian packaging branch

The Debian packaging git branch contains these updates to the upstream
.gitignore file(s).  This patch is autogenerated, to provide these
updates to users of the official Debian archive view of the package.

[dgit (11.11) update-gitignore]
---
diff --git a/.gitignore b/.gitignore
index e33a755..1737903 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,6 @@ coverage.txt
 tests/output/
 smoke.tests
 tools/optimizer-server/target
+
+/.pc/
+/_build/
