test-conversion: convert test-get-dependencies to new infrastructure

The test uses the ext4 module dependencies as the testcase, checking
both the number and the names of the returned modules.
diff --git a/testsuite/.gitignore b/testsuite/.gitignore
index 0c620aa..21fe518 100644
--- a/testsuite/.gitignore
+++ b/testsuite/.gitignore
@@ -4,6 +4,7 @@
 /.dirstamp
 /test-alias
 /test-blacklist
+/test-dependencies
 /test-init
 /test-loaded
 /test-modinfo