Merge pull request #1668 from alexanderkyte/bug1856

[runtime] Overwrite stacktrace for exception on re-throw. Fixes #1856.

diff --cc mono/mini/exceptions-amd64.c
Simple merge

diff --cc mono/mini/exceptions-arm.c
Simple merge

diff --cc mono/mini/exceptions-mips.c
Simple merge

diff --cc mono/mini/exceptions-ppc.c
Simple merge

diff --cc mono/mini/exceptions-s390x.c
Simple merge

diff --cc mono/mini/exceptions-x86.c
Simple merge

diff --cc mono/tests/Makefile.am
Simple merge