[Preset] Add linux crosscompile android preset

[AndrewSB]

The preset needs to include all of the following options passed to build-script:

    -R \                                       # Build in ReleaseAssert mode.
    --android \                                # Build for Android.
    --android-ndk $NDK_PATH \   # Path to an Android NDK.
    --android-api-level 21 \                   # The Android API level to target. Swift only supports 21 or greater.
    --android-icu-uc ${ARM_DIR}/libicuucswift.so \
    --android-icu-uc-include ${ARM_DIR}/icu/source/common \
    --android-icu-i18 ${ARM_DIR}/libicui18nswift.so \
    --android-icu-i18n-include ${ARM_DIR}/icu/source/i18n

I couldn't find other examples of presets that cross compile, @shahmishal is there a simple way to add this?

[shahmishal]

@AndrewSB You can try following:

[preset: buildbot_linux_crosscompile_android,tools=RA,stdlib=RD,build]
mixin-preset=buildbot_linux

release
assertions

dash dash

android
android-ndk=%(ndk_path)s
android-api-level=21
android-icu-uc=%(arm_dir)s/libicuucswift.so
android-icu-uc-include=%(arm_dir)s/icu/source/common
android-icu-i18=%(arm_dir)s/libicui18nswift.so
android-icu-i18n-include=%(arm_dir)s/icu/source/i18n

To test the preset try:

./utils/build-script --preset=buildbot_linux_crosscompile_android,tools=RA,stdlib=RD,build ndk_path=<NDK_PATH> arm_dir=<ARM_DIR>

[shahmishal]

@swift-ci smoke test

[shahmishal]

@swift-ci smoke test

[shahmishal]

You will need to update the test to support ndk_path and arm_dir, https://github.com/apple/swift/blob/4edb8d9baa50bddb4288b48eadb2b7867ba85e5b/utils/build_swift/tests/test_presets.py#L29

For example:

PRESET_DEFAULTS = {
    'arm_dir': 'arm',
    'darwin_toolchain_alias': 'Alias',
    'darwin_toolchain_bundle_identifier': 'BundleIdentifier',
    'darwin_toolchain_display_name': 'DisplayName',
    'darwin_toolchain_display_name_short': 'DispalyNameShort',
    'darwin_toolchain_version': '1.0',
    'darwin_toolchain_xctoolchain_name': 'default',
    'extra_swift_args': '',
    'install_destdir': '/tmp/install',
    'install_symroot': '/tmp/install/symroot',
    'install_toolchain_dir': '/tmp/install/toolchain',
    'installable_package': '/tmp/install/pkg',
    'ndk_path': '/path/to/ndk',
    'swift_install_destdir': '/tmp/install/swift',
    'symbols_package': '/path/to/symbols/package',
}

[AndrewSB]

@compnerd please smoke test

[compnerd]

@swift-ci please smoke test