build/boot/roms: check all targets before building

If one of them doesn't exist, error out.

Previously, a build would start but then it would
error out later on. This implements the mentality:

fail early, fail hard

Signed-off-by: Leah Rowe <leah@libreboot.org>

script/build/boot/roms

@@ -57,15 +57,23 @@ handle_targets()
 	[ "${first}" != "all" ] || boards="$(listitems config/coreboot)" || \
 	    err "handle_targets: Cannot get list of boards"
 
+	check_targets
+
 	for board in ${boards}; do
-		[ -d "config/coreboot/${board}/" ] || \
-			err "handle_targets: target not defined: ${board}"
 		./build boot roms_helper ${board}${opts} || \
 		    err "handle_targets ${board}${opts}: build error"
 		[ -d "bin/${board}" ] && targets="${board} ${targets}"
 	done
 }
 
+check_targets()
+{
+	for board in ${boards}; do
+		[ -d "config/coreboot/${board}/" ] || \
+			err "check_targets: target not defined: ${board}"
+	done
+}
+
 confirm_targets()
 {
 	[ -z "${targets}" ] && err "No ROM images were compiled."