CI: Store artifacts durring build

Add new option -A is added to tools/testbuild.sh that will take the
created build executable and store it in a folder for the config
that generated it under $ARTIFACTDIR which can be set via an
environment variable or defaulted to $(TOPDIR)/buildartifacts

This is also helpful for local testing because you can now run
tools/testbuild.sh -A sim.dat and have all of the simulation
targets generated without having to rebuild along the way.

In the GitHub Actions workflow the artifacs are uploaded
two two bundles one for macOS and one for Linux

Signed-off-by: Brennan Ashton <bashton@brennanashton.com>

.github/workflows/build.yml

@@ -161,8 +161,13 @@ jobs:
             export CCACHE_DIR=`pwd`/ccache
             mkdir $CCACHE_DIR
             cd sources/testing
-            ./cibuild.sh -c testlist/${{matrix.boards}}.dat
+            export ARTIFACTDIR=`pwd`/../../buildartifacts
+            ./cibuild.sh -A -c testlist/${{matrix.boards}}.dat
             ccache -s
+      - uses: actions/upload-artifact@v2
+        with:
+          name: linux-builds
+          path: buildartifacts/
 
   macOS:
     runs-on: macos-10.15
@@ -195,5 +200,10 @@ jobs:
           export CCACHE_DIR=`pwd`/ccache
           mkdir $CCACHE_DIR
           cd sources/testing
-          ./cibuild.sh -i -c testlist/${{matrix.boards}}.dat
+          export ARTIFACTDIR=`pwd`/../../buildartifacts
+          ./cibuild.sh -i -A -c testlist/${{matrix.boards}}.dat
           ccache -s
+      - uses: actions/upload-artifact@v2
+        with:
+          name: macos-builds
+          path: buildartifacts/