Add flutter config to macOS targets (#7756)
Add flutter config to macOS targets (#7756)

In 9345274 (#7642), //shell/platform/darwin:framework_shared was added
without the root flutter config, causing a build breakage in Fuchsia,
where flutter sits under //third_party/flutter as opposed to at the
root. The flutter root config is required to set -I../../third_party as
an include path.
jamesr/flutter_engine,Hixie/sky_engine,chinmaygarde/sky_engine,devoncarew/sky_engine,tvolkert/engine,cdotstout/sky_engine,Hixie/sky_engine,aam/engine,cdotstout/sky_engine,jamesr/flutter_engine,chinmaygarde/flutter_engine,rmacnak-google/engine,jason-simmons/sky_engine,chinmaygarde/sky_engine,cdotstout/sky_engine,flutter/engine,chinmaygarde/sky_engine,jason-simmons/sky_engine,rmacnak-google/engine,chinmaygarde/sky_engine,aam/engine,flutter/engine,chinmaygarde/flutter_engine,jamesr/flutter_engine,tvolkert/engine,cdotstout/sky_engine,aam/engine,aam/engine,devoncarew/sky_engine,jamesr/sky_engine,tvolkert/engine,aam/engine,jason-simmons/flutter_engine,chinmaygarde/sky_engine,jamesr/flutter_engine,cdotstout/sky_engine,flutter/engine,tvolkert/engine,chinmaygarde/sky_engine,tvolkert/engine,devoncarew/sky_engine,devoncarew/sky_engine,flutter/engine,devoncarew/sky_engine,rmacnak-google/engine,devoncarew/engine,Hixie/sky_engine,jamesr/flutter_engine,jason-simmons/flutter_engine,jason-simmons/flutter_engine,flutter/engine,jamesr/flutter_engine,mikejurka/engine,rmacnak-google/engine,chinmaygarde/flutter_engine,rmacnak-google/engine,tvolkert/engine,flutter/engine,tvolkert/engine,devoncarew/engine,jason-simmons/sky_engine,jamesr/flutter_engine,Hixie/sky_engine,jamesr/sky_engine,Hixie/sky_engine,jason-simmons/flutter_engine,Hixie/sky_engine,chinmaygarde/sky_engine,mikejurka/engine,jamesr/sky_engine,jamesr/flutter_engine,devoncarew/engine,devoncarew/engine,jamesr/sky_engine,Hixie/sky_engine,jamesr/sky_engine,jason-simmons/sky_engine,mikejurka/engine,jason-simmons/flutter_engine,jason-simmons/sky_engine,devoncarew/sky_engine,aam/engine,cdotstout/sky_engine,mikejurka/engine,devoncarew/engine,mikejurka/engine,mikejurka/engine,jason-simmons/sky_engine,chinmaygarde/flutter_engine,Hixie/sky_engine,aam/engine,chinmaygarde/flutter_engine,rmacnak-google/engine,devoncarew/engine,flutter/engine,jamesr/flutter_engine,devoncarew/engine,mikejurka/engine,jamesr/sky_engine,jason-simmons/flutter_engine,mikejurka/engine,cdotstout/sky_engine,jason-simmons/sky_engine,jamesr/sky_engine,flutter/engine,devoncarew/sky_engine,jason-simmons/flutter_engine,aam/engine,chinmaygarde/flutter_engine,mikejurka/engine,chinmaygarde/flutter_engine,jason-simmons/flutter_engine,rmacnak-google/engine