[platform][pc] change the default heap implementation for PC to dlmalloc
[platform][pc] change the default heap implementation for PC to dlmalloc

ErikCorryGoogle/lk,hollanderic/lkstuff,sndnvaps/lk,hollanderic/lkstuff,minglun-tsai/lk,travisg/lk,littlekernel/lk,ErikCorryGoogle/lk,littlekernel/lk,travisg/lk,travisg/lk,minglun-tsai/lk,travisg/lk,ErikCorryGoogle/lk,littlekernel/lk,ErikCorryGoogle/lk,sndnvaps/lk,minglun-tsai/lk,hollanderic/lkstuff,minglun-tsai/lk,hollanderic/lkstuff,littlekernel/lk,sndnvaps/lk,sndnvaps/lk,sndnvaps/lk