add saola button pin support, esp32 build with board_test

examples/device/cdc_msc_freertos/CMakeLists.txt

@@ -5,6 +5,10 @@ cmake_minimum_required(VERSION 3.5)
 # example src directory
 set(EXTRA_COMPONENT_DIRS "src")
 
+# TOP is absolute path to root directory of TinyUSB git repo
+set(TOP "../../..")
+get_filename_component(TOP "${TOP}" REALPATH)
+
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
 
 project(cdc_msc_freertos)