Find Heap Bound (bp #1648) (#1682)

* Refactor benchmark_code_compile.py to have job running utility

This provides a common Python interfaces for monitoring resource usage
of subprocesses

Co-authored-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>
(cherry picked from commit 038faf9f

)

* Add find_heap_bound.py script for finding minimum heap size

Co-authored-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>
(cherry picked from commit f7ae514f

)

# Conflicts:
#	.travis.yml

* Fixup for 1.3.x

Co-authored-by: Jack Koenig <koenig@sifive.com>