[lib][heap] make header c++ safe
[lib][heap] make header c++ safe

littlekernel/lk,nvll/lk,srodrig1/lk,hollanderic/lkstuff,travisg/lk,minglun-tsai/lk,minglun-tsai/lk,hollanderic/lkstuff,ErikCorryGoogle/lk,skabet/lk,nvll/lk,hollanderic/lkstuff,sndnvaps/lk,hollanderic/lkstuff,littlekernel/lk,GCrean/lk,travisg/lk,nvll/lk,ErikCorryGoogle/lk,GCrean/lk,GCrean/lk,sndnvaps/lk,sndnvaps/lk,skabet/lk,skabet/lk,littlekernel/lk,srodrig1/lk,srodrig1/lk,ErikCorryGoogle/lk,travisg/lk,minglun-tsai/lk,ErikCorryGoogle/lk,GCrean/lk,skabet/lk,sndnvaps/lk,minglun-tsai/lk,srodrig1/lk,sndnvaps/lk,skabet/lk,nvll/lk,srodrig1/lk,GCrean/lk,littlekernel/lk,nvll/lk,travisg/lk