wasm-linker: implement `__heap_base` symbol

When any object files provides an undefined reference to the __heap_base
symbol, we create a new defined symbol for it. During setupMemory we
set the virtual address of this symbol so it can be used for relocations.
This symbol represents where the heap starts and allocators can use
this value for its allocations when it needs to determine where the heap
lives.
c77ca91749Luuk de Gram committed on 1/12/2023, 7:50:18 PMparentf8d1efd
2 files changedLine totals unavailable