Bump the version of Coverity we are using to the latest. (#12398)

Also, report when we actually managed to download something, but the
name did not match what was expected.

coverity-scan.sh

@@ -21,7 +21,7 @@
 # COVERITY_SCAN_TOKEN="TOKEN taken from Coverity site"
 #
 # the absolute path of the cov-build - optional
-# COVERITY_BUILD_PATH="/opt/cov-analysis-linux64-2019.03/bin/cov-build"
+# COVERITY_BUILD_PATH="/opt/cov-analysis-linux64-2021.12/bin/cov-build"
 #
 # when set, the script will print on screen the curl command that submits the build to coverity
 # this includes the token, so the default is not to print it.
@@ -40,7 +40,7 @@ set -e
 INSTALL_DIR="/opt"
 
 # the version of coverity to use
-COVERITY_BUILD_VERSION="${COVERITY_BUILD_VERSION:-cov-analysis-linux64-2020.09}"
+COVERITY_BUILD_VERSION="${COVERITY_BUILD_VERSION:-cov-analysis-linux64-2021.12}"
 
 # TODO: For some reasons this does not fully load on Debian 10 (Haven't checked if it happens on other distros yet), it breaks
 source packaging/installer/functions.sh || echo "Failed to fully load the functions library"
@@ -147,6 +147,8 @@ installit() {
     run sudo tar -z -x -f "${TMP_DIR}/${COVERITY_BUILD_VERSION}.tar.gz" || exit 1
     rm "${TMP_DIR}/${COVERITY_BUILD_VERSION}.tar.gz"
     export PATH=${PATH}:${INSTALL_DIR}/${COVERITY_BUILD_VERSION}/bin/
+  elif find . -name "*.tar.gz" > /dev/null 2>&1; then
+    fatal "Downloaded coverity tool tarball does not appear to be the version we were expecting, exiting."
   else
     fatal "Failed to download coverity tool tarball!"
   fi