All platforms now specify whether to emit frame pointers by default, rather than
relying on default compiler options.

This CL moves the logic from config("default_stack_frames") into compiler.gni.
The former is actually the right place for the logic to live, but there exists
code that relies on whether a frame pointer is emitted by default. Right now,
that logic is being duplicated/guessed by the code in question. This CL at least
unifies the logic in a single location.

There current exists code that uses a preprocessor definition
HAVE_TRACE_STACK_FRAME_POINTERS. Despite the name, the code really wants to know
if most stacks can be unwound using stack pointers. I've renamed it to
CAN_UNWIND_WITH_FRAME_POINTERS. Arguably, any code that uses
CAN_UNWIND_WITH_FRAME_POINTERS is broken and should be removed, since it relies
on the assumption that all stacks will either have or not have frame pointers,
but that can vary TU by TU.

BUG=706116, 706654

Review-Url: https://codereview.chromium.org/2782063005
Cr-Commit-Position: refs/heads/master@{#462622}