[init] Improve support for Extension building by acknowledging CXXFLAGS; Sets...

[init] Improve support for Extension building by acknowledging CXXFLAGS; Sets -isysroot for macOS builds
2 jobs from better-macos-support in 11 minutes and 24 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #153809
docker
build_linux_36

00:11:01

70.0%
passed #153810
macosx
build_macosx_36

00:11:24

70.0%