cmake: make sure headers are not in api/ subdir
cmake: make sure headers are not in api/ subdir

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

noahchense/mraa,seem-sky/mraa,jontrulson/mraa,timrtoo/Intel,ProfFan/mraa,alext-mkrs/mraa,stefan-andritoiu/mraa-gpio-chardev,neuroidss/mraa,anonymouse64/mraa,intel-iot-devkit/mraa,stefan-andritoiu/mraa,spitfire88/mraa,ncrastanaren/mraa,yongli3/mraa,stefan-andritoiu/mraa-gpio-chardev,ncrastanaren/mraa,mircea/mraa,anonymouse64/mraa,Pillar1989/mraa,andreivasiliu2211/mraa,g-vidal/mraa,neuberfran/mraa,KurtE/mraa,yongli3/mraa,neuberfran/mraa,alex1818/mraa,noahchense/mraa,nioinnovation/mraa,stefan-andritoiu/mraa,malikabhi05/mraa,andreivasiliu2211/mraa,anonymouse64/mraa,spitfire88/mraa,damcclos/mraa,alext-mkrs/mraa,alext-mkrs/mraa,w4ilun/mraa,noahchense/mraa,SyrianSpock/mraa,w4ilun/mraa,intel-iot-devkit/mraa,Propanu/mraa,allela-roy/mraa,matt-auld/mraa,petreeftime/mraa,Hbrinj/mraa,sundw2014/mraa,w4ilun/mraa,arunlee77/mraa,sergev/mraa,neuberfran/mraa,Kiritoalex/mraa,Meirtz/mraa,malikabhi05/mraa,seem-sky/mraa,arunlee77/mraa,whbruce/mraa,SyrianSpock/mraa,arfoll/mraa,KurtE/mraa,nioinnovation/mraa,arunlee77/mraa,Hbrinj/mraa,Meirtz/mraa,tripzero/mraa,Jon-ICS/mraa,allela-roy/mraa,Meirtz/mraa,arfoll/mraa,Kiritoalex/mraa,smileboywtu/mraa,noahchense/mraa,Kiritoalex/mraa,nioinnovation/mraa,intel-iot-devkit/mraa,g-vidal/mraa,jontrulson/mraa,w4ilun/mraa,petreeftime/mraa,alexandru-elisei/mraa,intel-iot-devkit/mraa,smileboywtu/mraa,tripzero/mraa,alexandru-elisei/mraa,ncrastanaren/mraa,petreeftime/mraa,damcclos/mraa,tripzero/mraa,jontrulson/mraa,ncrastanaren/mraa,andreivasiliu2211/mraa,alex1818/mraa,pctj101/mraa,yangjae/mraa,whbruce/mraa,KurtE/mraa,zBMNForks/mraa,sundw2014/mraa,arfoll/mraa,seem-sky/mraa,stefan-andritoiu/mraa-gpio-chardev,damcclos/mraa,pctj101/mraa,arfoll/mraa,sergev/mraa,stefan-andritoiu/mraa,yoyojacky/mraa,Jon-ICS/mraa,ProfFan/mraa,timrtoo/Intel,Propanu/mraa,sergev/mraa,yoyojacky/mraa,STANAPO/mraa,malikabhi05/mraa,g-vidal/mraa,alexandru-elisei/mraa,Propanu/mraa,sundw2014/mraa,allela-roy/mraa,neuberfran/mraa,STANAPO/mraa,stefan-andritoiu/mraa-gpio-chardev,Jon-ICS/mraa,Hbrinj/mraa,seem-sky/mraa,KurtE/mraa,sundw2014/mraa,smileboywtu/mraa,yangjae/mraa,alext-mkrs/mraa,sergev/mraa,neuroidss/mraa,jontrulson/mraa,ProfFan/mraa,KurtE/mraa,whbruce/mraa,seem-sky/mraa,arfoll/mraa,spitfire88/mraa,g-vidal/mraa,Hbrinj/mraa,alexandru-elisei/mraa,whbruce/mraa,ncrastanaren/mraa,SyrianSpock/mraa,spitfire88/mraa,noahchense/mraa,arunlee77/mraa,yongli3/mraa,Propanu/mraa,timrtoo/Intel,malikabhi05/mraa,alex1818/mraa,pctj101/mraa,yangjae/mraa,zBMNForks/mraa,STANAPO/mraa,yongli3/mraa,Pillar1989/mraa,mircea/mraa,pctj101/mraa,mircea/mraa,pctj101/mraa,alexandru-elisei/mraa,alext-mkrs/mraa,stefan-andritoiu/mraa,stefan-andritoiu/mraa,timrtoo/Intel,neuroidss/mraa,timrtoo/Intel,sergev/mraa,zBMNForks/mraa,jontrulson/mraa,matt-auld/mraa,g-vidal/mraa,yangjae/mraa,andreivasiliu2211/mraa,neuberfran/mraa,yongli3/mraa,stefan-andritoiu/mraa-gpio-chardev,Propanu/mraa,sundw2014/mraa,intel-iot-devkit/mraa,ProfFan/mraa,Pillar1989/mraa,petreeftime/mraa,malikabhi05/mraa,matt-auld/mraa,yoyojacky/mraa