Improve run-ravenwood-tests.sh

- Add `-b` -- build only option.
- Print the command before executing it.
- Clean up the diff output.

Flag: EXEMPT host test change only
Bug: 292141694
Test: manual test
Change-Id: I104f7c38ea5a87c75288b270f39338a1eba53c59
diff --git a/ravenwood/scripts/run-ravenwood-tests.sh b/ravenwood/scripts/run-ravenwood-tests.sh
index fe2269a..27c5ea1 100755
--- a/ravenwood/scripts/run-ravenwood-tests.sh
+++ b/ravenwood/scripts/run-ravenwood-tests.sh
@@ -33,7 +33,7 @@
 exclude_re=""
 smoke_exclude_re=""
 dry_run=""
-while getopts "sx:f:dt" opt; do
+while getopts "sx:f:dtb" opt; do
 case "$opt" in
     s)
         # Remove slow tests.
@@ -52,8 +52,13 @@
         dry_run="echo"
         ;;
     t)
+        # Redirect log to terminal
         export RAVENWOOD_LOG_OUT=$(tty)
         ;;
+    b)
+        # Build only
+        ATEST=m
+        ;;
     '?')
         exit 1
         ;;
@@ -99,11 +104,16 @@
 
 # Calculate the removed tests.
 
-diff="$(diff  <(echo "${all_tests[@]}" | tr ' ' '\n') <(echo "${targets[@]}" | tr ' ' '\n') )"
+diff="$(diff  <(echo "${all_tests[@]}" | tr ' ' '\n') <(echo "${targets[@]}" | tr ' ' '\n') | grep -v [0-9] )"
 
 if [[ "$diff" != "" ]]; then
     echo "Excluded tests:"
     echo "$diff"
 fi
 
-$dry_run ${ATEST:-atest} "${targets[@]}"
+run() {
+    echo "Running: ${@}"
+    "${@}"
+}
+
+run $dry_run ${ATEST:-atest} "${targets[@]}"