QIR runtime heap alloc and heap free functions removed

[Patil2099]

Fixes #702

[swernli]

This is the right start, but there are a few other spots with code that can be removed as well. Now that __quantum__rt__heap_alloc and __quantum__rt__heap_free are removed, the declaration and implementation of the internal functions backing them can also be removed. Those are located in these two places:

qsharp-runtime/src/Qir/Runtime/lib/QIR/bridge-rt.ll

Lines 40 to 41 in 380003f

	declare i8* @quantum__rt__heap_alloc(i64)
	declare void @quantum__rt__heap_free(i8*)

qsharp-runtime/src/Qir/Runtime/lib/QIR/utils.cpp

Lines 25 to 47 in 380003f

	char* quantum__rt__heap_alloc(uint64_t size) // NOLINT
	{
	char* buffer = new (std::nothrow) char[size];
	if(buffer == nullptr)
	{
	quantum__rt__fail(quantum__rt__string_create("Allocation Failed"));
	}
	#ifndef NDEBUG
	UseMemoryTracker().insert(buffer);
	#endif
	return buffer;
	}
	// Release a block of allocated heap memory.
	void quantum__rt__heap_free(char* buffer) // NOLINT
	{
	#ifndef NDEBUG
	auto iter = UseMemoryTracker().find(buffer);
	assert(iter != UseMemoryTracker().end());
	UseMemoryTracker().erase(iter);
	#endif
	delete[] buffer;
	}

With that done, there are no more uses of the MemoryTracker defined at the top of utils.cpp, so that can be removed too.

[ghost]

All CLA requirements met.

[swernli]

Thanks for the quick updates! The changes look good to me, I'll formally sign off to unblock merge once the issue is triaged.

[Patil2099]

Can you review it again? @swernli

[swernli]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[swernli]

Apologies, @Patil2099, we seem to be having some problems in the build pipeline unrelated to this change. Hopefully I can get a clean build soon.

[swernli]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).