build: fix builds when first_api_level isn't defined as property

Bug: 67965044
Test: Build pixel
Merged-In: I4bce5a4f4d0751a30bf7abda0da5e7d73313c9ef
Change-Id: I4bce5a4f4d0751a30bf7abda0da5e7d73313c9ef
Signed-off-by: Sandeep Patil <sspatil@google.com>
(cherry picked from commit b79196f0ca4f553bd4dd9109d1a8a71c623872da)
diff --git a/core/Makefile b/core/Makefile
index fe397cf..e2647ea 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -380,7 +380,7 @@
 	@echo Target vendor buildinfo: $@
 	@mkdir -p $(dir $@)
 	$(hide) echo > $@
-	$(hide) grep 'ro.product.first_api_level' $(intermediate_system_build_prop) >> $@
+	$(hide) grep 'ro.product.first_api_level' $(intermediate_system_build_prop) >> $@ || true
 	$(hide) echo ro.vendor.build.date=`$(DATE_FROM_FILE)`>>$@
 	$(hide) echo ro.vendor.build.date.utc=`$(DATE_FROM_FILE) +%s`>>$@
 	$(hide) echo ro.vendor.build.fingerprint="$(BUILD_FINGERPRINT_FROM_FILE)">>$@