chore: update gitignore list (#9437)

Updated the gitignore list with the command : `go run scripts/generate-gitignores.go`

options/gitignore/Autotools

@@ -41,3 +41,9 @@ m4/ltoptions.m4
 m4/ltsugar.m4
 m4/ltversion.m4
 m4/lt~obsolete.m4
+
+# Generated Makefile 
+# (meta build system like autotools, 
+# can automatically generate from config.status script
+# (which is called by configure script))
+Makefile