Make pgm_read_byte() and pgm_read_word() usable from c files.
Make pgm_read_byte() and pgm_read_word() usable from c files.

The two defines used reinterpret_cast<> which is only available when
compiling with c++. Now using plain old c casts instead.

quertenmont/Arduino,lrmoreno007/Arduino,toastedcode/esp8266-Arduino,me-no-dev/Arduino,edog1973/Arduino,edog1973/Arduino,edog1973/Arduino,esp8266/Arduino,esp8266/Arduino,edog1973/Arduino,Adam5Wu/Arduino,Adam5Wu/Arduino,KaloNK/Arduino,Lan-Hekary/Arduino,KaloNK/Arduino,jes/Arduino,sticilface/Arduino,wemos/Arduino,hallard/Arduino,martinayotte/ESP8266-Arduino,gguuss/Arduino,quertenmont/Arduino,Lan-Hekary/Arduino,esp8266/Arduino,hallard/Arduino,Juppit/Arduino,lrmoreno007/Arduino,Links2004/Arduino,NextDevBoard/Arduino,NextDevBoard/Arduino,quertenmont/Arduino,wemos/Arduino,martinayotte/ESP8266-Arduino,hallard/Arduino,wemos/Arduino,sticilface/Arduino,NullMedia/Arduino,toastedcode/esp8266-Arduino,me-no-dev/Arduino,gguuss/Arduino,martinayotte/ESP8266-Arduino,KaloNK/Arduino,wemos/Arduino,lrmoreno007/Arduino,esp8266/Arduino,KaloNK/Arduino,NullMedia/Arduino,Lan-Hekary/Arduino,Adam5Wu/Arduino,Juppit/Arduino,lrmoreno007/Arduino,Links2004/Arduino,esp8266/Arduino,NullMedia/Arduino,wemos/Arduino,jes/Arduino,Juppit/Arduino,quertenmont/Arduino,NextDevBoard/Arduino,toastedcode/esp8266-Arduino,quertenmont/Arduino,NullMedia/Arduino,Lan-Hekary/Arduino,Juppit/Arduino,Links2004/Arduino,sticilface/Arduino,jes/Arduino,Adam5Wu/Arduino,NextDevBoard/Arduino,edog1973/Arduino,lrmoreno007/Arduino,toastedcode/esp8266-Arduino,gguuss/Arduino,NullMedia/Arduino,Juppit/Arduino,me-no-dev/Arduino,me-no-dev/Arduino,Links2004/Arduino,KaloNK/Arduino,jes/Arduino,martinayotte/ESP8266-Arduino,martinayotte/ESP8266-Arduino,NextDevBoard/Arduino,jes/Arduino,hallard/Arduino,Adam5Wu/Arduino,hallard/Arduino,toastedcode/esp8266-Arduino,Lan-Hekary/Arduino,sticilface/Arduino,Links2004/Arduino,gguuss/Arduino,gguuss/Arduino,sticilface/Arduino,me-no-dev/Arduino