Address comments from last review

images/wkdev_sdk/Containerfile

@@ -83,12 +83,12 @@ RUN sed -i 's/^Types: deb$/Types: deb deb-src/' /etc/apt/sources.list.d/ubuntu.s
 # Add Rust environment.
 ENV RUSTUP_HOME="/opt/rust" \
     CARGO_HOME="/opt/rust" \
-    PATH="/opt/rust/.cargo/bin:${PATH}"
+    PATH="/opt/rust/bin:${PATH}"
 
 RUN rustup default stable && \
     rustup component remove rust-docs && \
     cargo install --root /usr/local --version 0.8.1 --locked sccache && \
-    cargo install --root /usr/local cargo-c
+    cargo install --root cargo-c
 
 # Copy jhbuild helper files and do the initial build & install
 COPY /jhbuild/jhbuildrc /etc/xdg/jhbuildrc
@@ -137,5 +137,8 @@ RUN export QT_VERSION=$(qmake6 -query QT_VERSION) && \
       ln -s ${directory} ${directory}/${QT_VERSION}  >/dev/null 2>&1 || true; \
     done
 
+# Check GStreamer plugins are installed.
+RUN gst-inspect-1.0
+
 # Switch back to interactive prompt, when using apt.
 ENV DEBIAN_FRONTEND dialog