Make iasl option check work with older versions of iasl.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
diff --git a/Makefile b/Makefile
index 72ee152..45ea48a 100644
--- a/Makefile
+++ b/Makefile
@@ -221,7 +221,7 @@
################ DSDT build rules
-iasl-option=$(shell if "$(1)" "$(2)" -h > /dev/null 2>&1 \
+iasl-option=$(shell if test -z "`$(1) $(2) 2>&1 > /dev/null`" \
; then echo "$(2)"; else echo "$(3)"; fi ;)
$(OUT)%.hex: src/%.dsl ./tools/acpi_extract_preprocess.py ./tools/acpi_extract.py