Reverse IS_EXTERNAL check, and guard libedgetpu

- Seems to me like these checks were backwards: without IS_EXTERNAL set,
edgetpu-api is no longer a valid build target.
- Also, add libedgetpu to the guarded set that won't work externally.

Change-Id: I3d52e5703bec5426b705f9dd77e78f260ae8b4c3
diff --git a/packages.mk b/packages.mk
index 5bdcfda..5500b09 100644
--- a/packages.mk
+++ b/packages.mk
@@ -131,9 +131,8 @@
 
 $(eval $(call make-pbuilder-package-target,base-files,packages/base-files))
 
+ifeq ($(IS_EXTERNAL),)
 $(eval $(call make-pbuilder-package-target,libedgetpu,libedgetpu))
-
-ifneq ($(IS_EXTERNAL),)
 $(eval $(call make-pbuilder-package-target,edgetpu-api,packages/edgetpu-api,libedgetpu))
 endif
 
diff --git a/rootfs.mk b/rootfs.mk
index 15e15e5..91796c3 100644
--- a/rootfs.mk
+++ b/rootfs.mk
@@ -39,8 +39,8 @@
 	libedgetpu \
 	uboot-imx
 
-ifneq ($(IS_EXTERNAL),)
-BASE_PACKAGES += edgetpu-api
+ifeq ($(IS_EXTERNAL),)
+BASE_PACKAGES += libedgetpu edgetpu-api
 endif
 
 GUI_PACKAGES := \