Add changelog

Author: sergv

changelog.d/pr-11005.md

@@ -0,0 +1,9 @@
+---
+synopsis: Deduplicate hsc2hs command-line arguments
+packages: [Cabal]
+prs: 11005
+---
+
+Fix a problem where `hsc2hs` becomes non-operational on packages with
+lots of dependencies and projects that specify lots of
+`extra-include-dirs` or `extra-lib-dirs`.