Add basic rpi2040 blink demo app

Phew, things build!  Lets check in how far we got.

Change-Id: Id82e2f4c73eed6620b2b4661726f931e79a6b0c1
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
diff --git a/debian/opencv.BUILD b/debian/opencv.BUILD
index 56b3cac..32ecec2 100644
--- a/debian/opencv.BUILD
+++ b/debian/opencv.BUILD
@@ -472,6 +472,7 @@
             "usr/lib/arm-linux-gnueabihf/libgomp.so.1",
         ],
         "cortex-m": [],
+        "cortex-m0plus": [],
     }),
     hdrs = glob([
         "usr/include/opencv/**",