[Mtk][N0][GMS] Android7.0添加GMS包W

Android 7.0添加GMS包后，编译时会出现WebViewGoogle报错：

ro.product.first_api_level property is undefined

这行log出自脚本文件：

\vendor\google\apps\WebViewGoogle\Android.mk

# make sure to include correct WebView binary: full or stub
_list_of_old_api_levels := 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
ifneq (,$(filter $(PLATFORM_SDK_VERSION),$(_list_of_old_api_levels)))
  # WebView apks in this folder are for N or later platforms only, stop building
  $(error PLATFORM_SDK_VERSION must be equal to or greater than 24)
endif

_ro_property_string := $(filter ro.product.first_api_level=%,$(ADDITIONAL_BUILD_PROPERTIES))

ifdef _ro_property_string
  _first_api_level := $(word 2,$(subst =,$(space),$(_ro_property_string)))
else
  # if the first_api_level property is undefined, stop building
  $(error ro.product.first_api_level property is undefined) 
endif

如上脚本倒数第二行，即是log出处。

解决办法：

在 _ro_property_string 那行脚本上面插入新脚本：

ADDITIONAL_BUILD_PROPERTIES += ro.product.first_api_level=24

_ro_property_string := $(filter ro.product.first_api_level=%,$(ADDITIONAL_BUILD_PROPERTIES))