Fix app build for Android against prebuilt version

[borissoft]

Description

Fix app build for Android against prebuilt Firebase C++ SDK.

Android NDK 21 says: fatal error: 'app/src/include/firebase/future.h' file not found

Testing

Building was tested on my local computer.

Type of Change

• Bug fix. Add the issue # below if applicable.
• New feature. A non-breaking change which adds functionality.
• Other, such as a build process or documentation change.

Notes

Look at the files in app/src/include/firebase/ directory.
File doesn't contain app/src/include/ prefix inside #include paths.
Also removing the prefix app/src/include/ from line 25 of app/src/include/google_play_services/availability.h has solved my build problem.

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[github-actions]

❌  Integration test FAILED

Requested by @jonsimantov on commit refs/pull/736/merge
Last updated: Fri Nov 5 14:30 PDT 2021
View integration test log & download artifacts

Failures	Configs
database	[BUILD] [ERROR] [MacOS] [openssl]
firestore	[TEST] [ERROR] [Android] [windows] [android_target]

Add flaky tests to go/fpl-cpp-flake-tracker

[borissoft]

@googlebot I signed it!

[borissoft]

@jonsimantov Are you sure the tests failed because of my commit?

[jonsimantov]

@jonsimantov Are you sure the tests failed because of my commit?

Looks like unrelated issues, I'll remove the "failed" flag.

[jonsimantov]

Change looks good, could you please add a PR description and then I'll approve it.

Thanks for your contribution!

[borissoft]

@jonsimantov Okay, done.