Place TARGET_FS_CONFIG_GEN passwd/group files in /vendor/etc

These entries are vendor provided and belong on the /vendor partition.

Bug: 27999086
Test: end to end user/group check via config.fs and getpwnam, etc.
Change-Id: I9a5d56da594bf0d04de2b9ce7fd7d9a8151d4682
diff --git a/tools/fs_config/Android.mk b/tools/fs_config/Android.mk
index 3773d38..1247896 100644
--- a/tools/fs_config/Android.mk
+++ b/tools/fs_config/Android.mk
@@ -261,6 +261,7 @@
 
 LOCAL_MODULE := passwd
 LOCAL_MODULE_CLASS := ETC
+LOCAL_VENDOR_MODULE := true
 
 include $(BUILD_SYSTEM)/base_rules.mk
 
@@ -279,6 +280,7 @@
 
 LOCAL_MODULE := group
 LOCAL_MODULE_CLASS := ETC
+LOCAL_VENDOR_MODULE := true
 
 include $(BUILD_SYSTEM)/base_rules.mk