otool -L libfontconfig.1.dylib

macOS標準(LDFLAGSは特になし)
$ otool -L libfontconfig.1.dylib
libfontconfig.1.dylib:
/usr/local/lib/libfontconfig.1.dylib (compatibility version 12.0.0, current version 12.1.0)
/usr/local/opt/freetype/lib/libfreetype.6.dylib (compatibility version 24.0.0, current version 24.4.0)
/usr/lib/libxml2.2.dylib (compatibility version 10.0.0, current version 10.9.0)

Homebrewのを指定(LDFLAGSで)
$ otool -L libfontconfig.1.dylib
libfontconfig.1.dylib:
/usr/local/lib/libfontconfig.1.dylib (compatibility version 12.0.0, current version 12.1.0)
/usr/local/opt/freetype/lib/libfreetype.6.dylib (compatibility version 24.0.0, current version 24.4.0)
/usr/local/opt/libxml2/lib/libxml2.2.dylib (compatibility version 12.0.0, current version 12.10.0)

ちゃんと切り替わってる／選択されてるね

てか、同じ2.2やんけっ
>デフォの libxml2 が古いようなので
って、
*** SAX1 support in libxml2 is required. enable it or use expat instead.
が出てるから？？
(fontconfigのconfigureはなんかクセが強いw)