macOS arm64 build

[keyle]

file libcmark-gfm.dylib                                                                                       cmark-gfm [master]
libcmark-gfm.dylib: Mach-O 64-bit dynamically linked shared library x86_64

How do I make this lib arm64 so that it can be linked in a arm64 macOS C app?

I've tried the usual c flags ... -target arm64-apple-macosx without much success.

Thanks