CMake: install(EXPORT) fails with BUILD_SHARED_LIBS=OFF

[lnagel]

Problem

When building with BUILD_SHARED_LIBS=OFF, the install(EXPORT libdigidocppExport ...) at src/CMakeLists.txt:256 fails because the export set includes digidocpp but not its private link dependencies (minizip, digidocpp_priv/digidocpp_tsl). CMake requires all linked targets to be in the export set for static libraries.

Error:

CMake Error: install(EXPORT "libdigidocppExport" ...) includes target "digidocpp"
which requires target "minizip" that is not in any export set.

Suggested fix

Either:

1. Add the private targets (minizip, digidocpp_priv) to the export set, or
2. Guard the export install with a static build check:

if(BUILD_SHARED_LIBS AND NOT ANDROID)
    install(EXPORT libdigidocppExport ...)
endif()

Current workaround

Setting ANDROID=TRUE before add_subdirectory() skips the export install via the existing if(NOT ANDROID) guard at line 264, but this is a misuse of that flag.

Context

Found while building Python bindings with BUILD_SHARED_LIBS=OFF for self-contained wheel packaging. Affects v4.3.0 and current main.