heap_profiler.cpp a few bugs

In file heap_profiler.cpp

member functions like size(), hash(), operator==, need const.
Consider replacing private HashTable implementation with standard one.

L479 bounds on j are infinite if numFrames < skipEndFrames.

L486 first paren isn't necessarily start of function params.
for example, "_Z1gIEPFviEv" demangles to "void (*g<>())(int)", a function returning a function pointer. Maybe just don't demangle.

L502 StringData receives a dangling reference.