-DZMQ_STATIC required externally when using a static libzmq in mingw, is not set in pkg-config

[ghost]

Issue description

for using a static libzmq with mingw -DZMQ_STATIC is required by some defines in zmq.h, but it is not set by pkg-config. However, this can't be fixed right now, as there is no Cflags.private in pkg-config, see https://bugs.freedesktop.org/show_bug.cgi?id=47996

Environment

• libzmq version (commit hash if unreleased): 4.2.2
• OS: linux/any

[bluca]

Thanks - given that ticket is 4 years old I doubt pkg-config will ever implement cflags.private, unfortunately, so given you have documented it in INSTALL I'll close this issue