Build: Add unicorn as a submodule and build it if needed

Adds a cmake custom target that will build unicorn on first compile and
uses this in the build scripts as well. Updates Appveyor and Travis
build scripts to work with the new unicorn build, and updates the paths
to all of the different artifacts.

1 files changed, 0 insertions, 0 deletions

diff --git a/externals/unicorn b/externals/unicorn
new file mode 160000
+Subproject 73f45735354396766a4bfb26d0b96b06e5cf31b