iosbuild: add success/failure output

Change-Id: I84492f68752321f0266141666e2672ed2da5f509

build/make/iosbuild.sh

@@ -172,8 +172,13 @@ build_framework() {
 # Trap function. Cleans up the subtree used to build all targets contained in
 # $TARGETS.
 cleanup() {
+  local readonly res=$?
   cd "${ORIG_PWD}"
 
+  if [ $res -ne 0 ]; then
+    elog "build exited with error ($res)"
+  fi
+
   if [ "${PRESERVE_BUILD_OUTPUT}" != "yes" ]; then
     rm -rf "${BUILD_ROOT}"
   fi
@@ -194,6 +199,10 @@ cat << EOF
 EOF
 }
 
+elog() {
+  echo "${0##*/} failed because: $@" 1>&2
+}
+
 vlog() {
   if [ "${VERBOSE}" = "yes" ]; then
     echo "$@"
@@ -255,3 +264,5 @@ EOF
 fi
 
 build_framework "${TARGETS}"
+echo "Successfully built '${FRAMEWORK_DIR}' for:"
+echo "         ${TARGETS}"