Another try at getting CI right

It seems like there are some things that mysterious are not
dependencies of one of my packages (probably Qt) that must be
supplied *in the system* rather than through the normal process, and
also cannot be expressed by Qt (or whatever), which is strange, but I
am going to try adding it in via "apt install".

Also add missing Boost.Spirit, Boost.Test, and Eigen3

.github/workflows/ci.yml

@@ -48,12 +48,18 @@ jobs:
       with:
         submodules: true
 
-    - name: Restore from cache and setup vcpkg executable and data files.
+    - name: Set up vcpkg and install our dependencies
       uses: lukka/run-vcpkg@v11
       with:
         vcpkgJsonGlob: 'vcpkg.json'
         runVcpkgInstall: true
 
+    - name: Get runtime system dependencies for building Qt (?)
+      if: matrix.c_compiler != 'cl'
+      shell: bash
+      run: |
+        apt install libxi-dev libxtst-dev
+
     - name: Set reusable strings
       # Turn repeated input strings (such as the build output directory) into step outputs. These step outputs can be used throughout the workflow file.
       id: strings

vcpkg.json

@@ -4,8 +4,10 @@
   "dependencies": [
       "boost-program-options",
       "boost-config",
+      "boost-spirit",
+      "boost-test"
+      "eigen3",
       "qt5-base",
-      "tcl",
-      "libxtst"
+      "tcl"
   ]
 }