FROMLIST: egl: Use pkg-config for Android NDK build

It's possible to build Mesa for Android using the traditional
autotools workflow [1]. ChromiumOS fetches Android prebuilts and
puts them in a sysroot. We now want to use pkg-config to specify
the location of system headers and libraries [2].

To enable this, let's add the required pkg-config checks and link
against them.

[1] https://developer.android.com/ndk/guides/standalone_toolchain.html
[2] https://chromium-review.googlesource.com/#/c/403237/

v2: Bundle pkg-config checks together (Emil)
v3: Provide further context on standalone NDK Mesa build (Emil)

BUG=b/32077475
TEST=arc-mesa builds

CQ-DEPEND=CL:403237, CL:404150, CL:404151

Change-Id: Ia1cb9154b59e19e02a75de9642fbad7a440d54cc
Reviewed-on: https://chromium-review.googlesource.com/403315
Commit-Ready: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
2 files changed