Docker related updates
- configure/probe for docker
- TARGET_DIRS -> TARGET_LIST cleanup
- new fedora-i386-cross and debian/tricore images
- test-mingw use SDL2/GTK3
# gpg: Signature made Tue 05 Jun 2018 16:32:53 BST
# gpg: using RSA key
FBD0DB095A9E2A44
# gpg: Good signature from "Alex Bennée (Master Work Key) <alex.bennee@linaro.org>"
# Primary key fingerprint: 6685 AE99 E751 67BC AFC8 DF35 FBD0 DB09 5A9E 2A44
* remotes/stsquad/tags/pull-docker-updates-050618-1:
docker: add debian/tricore image
docker: test-mingw: use SDL2 and GTK+3
docker: Add fedora-i386-cross image
Makefile: Rename TARGET_DIRS to TARGET_LIST
configure: add test for docker availability
docker: add "probe" command for configure
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>