Enable ro.moz.devinputjack for non-ICS gonk

This enables usage of the /dev/input headphone/mic jack events within Gecko.

Change-Id: I030c5833b945dd0307dd56339eeb4631d1a62b99

b2g_product.mk

@@ -40,6 +40,10 @@ PRODUCT_PROPERTY_OVERRIDES += \
   ro.moz.omx.hw.max_width=800 \
   ro.moz.omx.hw.max_height=480
 
+ifneq ($(PLATFORM_SDK_VERSION), 15)
+PRODUCT_PROPERTY_OVERRIDES += ro.moz.devinputjack=1
+endif
+
 ifneq ($(filter user userdebug, $(TARGET_BUILD_VARIANT)),)
 USE_JSMIN = 1
 endif