GPIO only HAL functions for Raspberry Pi

This example is based on the bcm2835 library from Mike McCauley

The bcm2835.[hc] files are under GPL v3 copyright.
taken from here:
http://www.airspayce.com/mikem/bcm2835/

The resulting code will work, bit will be slow because super user access is missing.
To speed up the exection, run the result unter super user either with "sudo" or 
by raising the rights of the generated executable:

sudo chown root:root ./main
sudo chmod u+s ./main