runtime: Switch to using the rust version of virtiofsd (all but power)

So far this has been done for x86_64.  Now that the support for building
and testing has been added for all arches, let's do the second part of
the switch.

We're still not done yet for powerpc, as some a virtifosd crash on the
rust version has been found by the maintainer.

Fixes: #4258, #4260

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>

snap/snapcraft.yaml

@@ -52,6 +52,36 @@ parts:
       curl -LO https://golang.org/dl/${tarfile}
       tar -xf ${tarfile} --strip-components=1
 
+  rustdeps:
+    after: [metadata]
+    plugin: nil
+    prime:
+      - -*
+    build-packages:
+      - curl
+    override-build: |
+      source "${SNAPCRAFT_PROJECT_DIR}/snap/local/snap-common.sh"
+
+      # put everything in stage
+      cd "${SNAPCRAFT_STAGE}"
+
+      version="$(${yq} r ${kata_dir}/versions.yaml languages.rust.meta.newest-version)"
+      if ! command -v rustup > /dev/null; then
+        curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain ${version}
+      fi
+
+      export PATH=${PATH}:${HOME}/.cargo/bin
+      rustup toolchain install ${version}
+      rustup default ${version}
+      if [ "${arch}" == "ppc64le" ] || [ "${arch}" == "s390x" ] ; then
+        [ ${arch} == "ppc64le"] && arch="powerpc64le"
+        rustup target add ${arch}-unknown-linux-gnu
+      else
+        rustup target add ${arch}-unknown-linux-musl
+        $([ "$(whoami)" != "root" ] && echo sudo) ln -sf /usr/bin/g++ /bin/musl-g++
+      fi
+      rustup component add rustfmt
+
   image:
     after: [godeps, qemu, kernel]
     plugin: nil
@@ -271,25 +301,26 @@ parts:
 
   virtiofsd:
     plugin: nil
-    after: [godeps]
+    after: [godeps, rustdeps]
     override-build: |
       source "${SNAPCRAFT_PROJECT_DIR}/snap/local/snap-common.sh"
 
-      # Currently, only one platform uses the new rust virtiofsd. The
-      # others make use of QEMU's C implementation.
+      # Currently, powerpc makes use of the QEMU's C implementation.
+      # The other platforms make use of the new rust virtiofsd.
       #
       # See "tools/packaging/scripts/configure-hypervisor.sh".
-      if [ "${arch}" = 'x86_64' ]
+      if [ "${arch}" == "ppc64le" ]
       then
-          echo "INFO: Building rust version of virtiofsd"
-      else
           echo "INFO: Building QEMU's C version of virtiofsd"
           # Handled by the 'qemu' part, so nothing more to do here.
           exit 0
+      else
+          echo "INFO: Building rust version of virtiofsd"
       fi
 
       cd "${kata_dir}"
 
+      export PATH=${PATH}:${HOME}/.cargo/bin
       # Download the rust implementation of virtiofsd
       tools/packaging/static-build/virtiofsd/build-static-virtiofsd.sh
       sudo install \