static-php-cli v3 support

[happystraw]

When v3 is released, Vendor Mode should be adopted in place of the existing hack-based approach.

• config/ext.json, config/sourcejson hack
• linux: copy webkit2gtk pkg-config file for dynamic link, see scripts/copy-pkgconfig.sh

  It may still be required to proceed in this way.

Base on: crazywhalecc/static-php-cli#961