build: add cache to ./configure with -C flag

Add the -C flag to ./configure to enable caching, reducing redundant
resource fetching during builds when packages and the machine remain
unchanged. Caching may cause issues only if applied across different machines
or if packages are modified, neither of which is the case during the build.

ci-build.sh

@@ -121,11 +121,11 @@ esac
 case "$ARCH" in
     linux*)
          echo
-         echo "--> Building with ./configure ${tests[0]} --enable-valgrind $*"
+         echo "--> Building with ./configure -C ${tests[0]} --enable-valgrind $*"
          echo
 
          # shellcheck disable=SC2086
-        ./configure ${tests[0]} --enable-valgrind $*
+        ./configure -C ${tests[0]} --enable-valgrind $*
 
         $MAKE CC="${CC}"
         if grep '^ID=' /etc/os-release | grep -q -e debian; then
@@ -140,7 +140,7 @@ esac
 for features in "${tests[@]}"
 do
     echo
-    echo "--> Building with ./configure ${features} $*"
+    echo "--> Building with ./configure -C ${features} $*"
     echo
 
     # shellcheck disable=SC2086