UBUNTU: [Packaging] checks/retpoline-check: Make 'skipretpoline' argument optional

Make the 'skipretpoline' argument optional and also more robust to match
the other checker scripts.

While at it, drop the invalid/unused 5th argument from the call site in
the rules file.

Signed-off-by: Juerg Haefliger <juerg.haefliger@canonical.com>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>

debian/rules.d/4-checks.mk

@@ -21,7 +21,7 @@ module-signature-check-%: $(stampdir)/stamp-install-%
 retpoline-check-%: $(stampdir)/stamp-install-%
 	@echo Debug: $@
 	$(DROOT)/scripts/checks/retpoline-check "$*" \
-		"$(prev_abidir)" "$(abidir)" "$(skip_checks)" "$(builddir)/build-$*"
+		"$(prev_abidir)" "$(abidir)" $(skip_checks)
 
 checks-%: module-check-% module-signature-check-% abi-check-% retpoline-check-%
 	@echo Debug: $@

debian/scripts/checks/retpoline-check

@@ -3,7 +3,12 @@
 flavour="$1"
 prev_abidir="$2"
 curr_abidir="$3"
-skipretpoline="$4"
+
+skipretpoline=${4:-}
+case "${skipretpoline,,}" in
+	1|true|yes) skipretpoline=true ;;
+	*) skipretpoline=false ;;
+esac
 
 echo "II: Checking retpoline indirections for $flavour...";