cmake: add option to disable example building
cmake: add option to disable example building

Signed-off-by: Brendan Le Foll <3e0e8c4069934e8b47d99704927a85c66c0ceb33@intel.com>

w4ilun/mraa,whbruce/mraa,damcclos/mraa,KurtE/mraa,Pillar1989/mraa,smileboywtu/mraa,ncrastanaren/mraa,alext-mkrs/mraa,Meirtz/mraa,alext-mkrs/mraa,w4ilun/mraa,stefan-andritoiu/mraa-gpio-chardev,yongli3/mraa,g-vidal/mraa,stefan-andritoiu/mraa,yongli3/mraa,matt-auld/mraa,Kiritoalex/mraa,g-vidal/mraa,stefan-andritoiu/mraa,yongli3/mraa,yoyojacky/mraa,ProfFan/mraa,Kiritoalex/mraa,stefan-andritoiu/mraa,STANAPO/mraa,alex1818/mraa,ProfFan/mraa,STANAPO/mraa,malikabhi05/mraa,stefan-andritoiu/mraa,allela-roy/mraa,spitfire88/mraa,nioinnovation/mraa,jontrulson/mraa,jontrulson/mraa,SyrianSpock/mraa,ncrastanaren/mraa,whbruce/mraa,yongli3/mraa,malikabhi05/mraa,allela-roy/mraa,petreeftime/mraa,alex1818/mraa,Propanu/mraa,allela-roy/mraa,jontrulson/mraa,anonymouse64/mraa,Hbrinj/mraa,andreivasiliu2211/mraa,Propanu/mraa,intel-iot-devkit/mraa,yoyojacky/mraa,arfoll/mraa,g-vidal/mraa,petreeftime/mraa,damcclos/mraa,SyrianSpock/mraa,anonymouse64/mraa,matt-auld/mraa,alex1818/mraa,arunlee77/mraa,Jon-ICS/mraa,stefan-andritoiu/mraa-gpio-chardev,mircea/mraa,jontrulson/mraa,smileboywtu/mraa,tripzero/mraa,ProfFan/mraa,damcclos/mraa,arunlee77/mraa,arunlee77/mraa,neuroidss/mraa,Propanu/mraa,intel-iot-devkit/mraa,whbruce/mraa,g-vidal/mraa,ncrastanaren/mraa,intel-iot-devkit/mraa,Meirtz/mraa,intel-iot-devkit/mraa,sergev/mraa,sergev/mraa,mircea/mraa,jontrulson/mraa,STANAPO/mraa,Hbrinj/mraa,nioinnovation/mraa,ncrastanaren/mraa,neuroidss/mraa,alext-mkrs/mraa,arfoll/mraa,stefan-andritoiu/mraa-gpio-chardev,zBMNForks/mraa,spitfire88/mraa,sergev/mraa,malikabhi05/mraa,sergev/mraa,petreeftime/mraa,arunlee77/mraa,KurtE/mraa,ncrastanaren/mraa,yongli3/mraa,andreivasiliu2211/mraa,petreeftime/mraa,arfoll/mraa,Hbrinj/mraa,Jon-ICS/mraa,Kiritoalex/mraa,stefan-andritoiu/mraa-gpio-chardev,Propanu/mraa,alext-mkrs/mraa,tripzero/mraa,stefan-andritoiu/mraa-gpio-chardev,malikabhi05/mraa,w4ilun/mraa,anonymouse64/mraa,andreivasiliu2211/mraa,w4ilun/mraa,KurtE/mraa,Propanu/mraa,neuroidss/mraa,zBMNForks/mraa,Pillar1989/mraa,yoyojacky/mraa,arfoll/mraa,smileboywtu/mraa,nioinnovation/mraa,matt-auld/mraa,KurtE/mraa,malikabhi05/mraa,Meirtz/mraa,mircea/mraa,spitfire88/mraa,spitfire88/mraa,andreivasiliu2211/mraa,SyrianSpock/mraa,g-vidal/mraa,stefan-andritoiu/mraa,arfoll/mraa,ProfFan/mraa,KurtE/mraa,tripzero/mraa,Pillar1989/mraa,intel-iot-devkit/mraa,whbruce/mraa,Hbrinj/mraa,sergev/mraa,Jon-ICS/mraa,alext-mkrs/mraa,zBMNForks/mraa