Add a new option to conserve stack space.

There are a few places where large data structures are put on the stack.
This causes failures when trying to dump threads using a smaller stack so
use an option to conserve stack space.

Tested by running these commands:

autoreconf -i
./configure

Verify that config.h has CONSERVE_STACK undefined since this is a host build.

autoreconf -i
android/conf_arm.sh

Verify that config.h has CONSERVE_STACK defined.

Built libunwind with both CONSERVE_STACK define and undefined.

Bug: 8410085
Change-Id: I9ec4dee656475650883176d8801430b7e312153c
5 files changed