build: set build fingerprint for all devices

* there's no per device way to add props to /system/build.prop
* adding it here is the only way so far

Change-Id: I8aba198c78ff80f0be7c9af7fc2454efab05e44a
diff --git a/build/fingerprint.mk b/build/fingerprint.mk
new file mode 100644
index 0000000..69256cd
--- /dev/null
+++ b/build/fingerprint.mk
@@ -0,0 +1,5 @@
+# Build fingerprint
+ifneq ($(BUILD_FINGERPRINT),)
+ADDITIONAL_BUILD_PROPERTIES += \
+    ro.build.fingerprint=$(BUILD_FINGERPRINT)
+endif