build(wiringpi): added top-level CMakeLists.txt

CMakeLists.txt

@@ -0,0 +1,8 @@
+cmake_minimum_required(VERSION 3.10)
+
+project(wiringPi_Main VERSION 0.1)
+
+add_subdirectory(wiringPi)
+add_subdirectory(devLib)
+add_subdirectory(wiringPiD)
+add_subdirectory(gpio)