Update array submodule and add generated files to gitignore

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: tchajed

.gitignore

@@ -23,4 +23,8 @@
 *.glob
 .coqdeps.d
 _RocqProject
+Makefile.coq
+Makefile.coq.conf
+.Makefile.coq.d
+.filestoinstall
 .lia.cache