Update assembly filter to handle LLVM comments

[wfchandler]

Fixes #406

The LLVM comments recently added to assembly are not handled by the existing filtering scripts, causing some labels to be removed incorrectly.

This commit makes the following updates:

• Fixes the assembly filtering to recognize labels with a comment on the same line
• Retain comments that are on their own line
  • For now I've retained the # %bb comments as seen in the example below. I'm not sure how much utility they provide, but they also don't create too much noise.
• Directive types that were previously removed will continue to be removed even if they have a comment
  • This removes the "Begin function..." comments added to .p2align directives, but still retains the standalone "End function" comments. I don't think this will be confusing as the filtering makes it easy to tell which function we're in. Below is an example for reference:

Raw

	.p2align	4, 0x90         # -- Begin function <T as core::any::Any>::get_type_id
	.type	<T as core::any::Any>::get_type_id,@function
<T as core::any::Any>::get_type_id: # @"<T as core::any::Any>::get_type_id"
	.cfi_startproc
# %bb.0:
	movabsq	$7549865886324542212, %rax # imm = 0x68C68305D036CB04
	retq
.Lfunc_end0:
	.size	<T as core::any::Any>::get_type_id, .Lfunc_end0-<T as core::any::Any>::get_type_id
	.cfi_endproc
                                        # -- End function

Filtered

<T as core::any::Any>::get_type_id: # @"<T as core::any::Any>::get_type_id"
# %bb.0:
	movabsq	$7549865886324542212, %rax # imm = 0x68C68305D036CB04
	retq
                                        # -- End function

[shepmaster]

@scottmcm do you have any opinions on the improved output?

[wfchandler]

Interesting paper re reordering basic blocks (bb):

https://arxiv.org/abs/1809.04676