Set CAIRO_WIN32_STATIC_BUILD when doing a static build on windows
When doing static builds of poppler on Windows, cairo is typically built from source using a Meson subproject.
The CAIRO_WIN32_STATIC_BUILD define needs to be set when linking statically against cairo. It can either be set in poppler's own meson.build, or directly in cairo's meson.build, if my understanding is correct.
The define is only set when default_library is static and the host machine system is windows, as it is not useful/desirable in other scenarios.
(There's no public meson.build files for poppler yet - I'll submit them to wrapdb soon).