git submodules ignore untracked files

.gitmodules

@@ -22,15 +22,18 @@
 [submodule "unittests/googletest"]
 	path = unittests/googletest
 	url = https://github.com/google/googletest.git
+	ignore = untracked
 [submodule "src/lib/matrix"]
 	path = src/lib/matrix
 	url = https://github.com/PX4/Matrix.git
 [submodule "src/lib/DriverFramework"]
 	path = src/lib/DriverFramework
 	url = https://github.com/PX4/DriverFramework.git
+	ignore = untracked
 [submodule "src/lib/ecl"]
 	path = src/lib/ecl
 	url = https://github.com/PX4/ecl.git
+	ignore = untracked
 [submodule "cmake/cmake_hexagon"]
 	path = cmake/cmake_hexagon
 	url = https://github.com/ATLFlight/cmake_hexagon