Fix build with ICU 76

[cho-m]

Due to unicode-org/icu@199bc82, ICU 76 no longer adds icu-uc by default. This causes linker errors for undefined symbols like icu_76::UnicodeString::doReplace(...), referenced from: zim::removeAccents(...) in tools.cpp.o.

Meson will automatically flatten the dependencies list as documented at https://mesonbuild.com/Reference-manual_functions.html#build_target

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There didn't seem to be any usage of icu_dep methods and only passing it to dependencies: [..., icu_dep, ...]. If this changes, then may need to use multiple variables.

[cho-m]

Linux CI has an unrelated failure trying to find software-properties-common which isn't available in Debian Trixie.

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Windows CI has a related failure as it looks like icu-i18n.pc is manually created.

Maybe a workaround like:

dependency('icu-uc', required: host_machine.system() != 'windows', static:static_linkage)

or

icu_dep = [dependency('icu-i18n', required:xapian_dep.found(), static:static_linkage)]
if build_machine.system() != 'windows'
    icu_dep += [dependency('icu-uc', required:xapian_dep.found(), static:static_linkage)]
endif

[kelson42]

@cho-m Thank you for your PR. CI was OK a month ago, I will have a look and try to fix them so we can test your PR properly.

[kelson42]

@cho-m I have fixed a few things but we have a serious problem with the Windows CI. The CI for Windows does not pass for the moment on main either... although it does not block at the line you have added. My that be that your code is not compatible with older version of libicu? https://github.com/kiwix/kiwix-build/blob/main/kiwixbuild/dependencies/icu4c.py

[cho-m]

code is not compatible with older version of libicu? https://github.com/kiwix/kiwix-build/blob/main/kiwixbuild/dependencies/icu4c.py

The official (Unix) pkgconfig files are compatible (icu-uc.pc has been around as long as icu-i18n.pc, i.e. ICU 59 - unicode-org/icu@d390758)

However, Windows build is using custom/3rd-party pkgconfig files. Ideally would have provided other pkgconfig files like Cygwin (https://cygwin.com/packages/x86_64/libicu-devel/libicu-devel-73.2-1)

    2023-08-03 01:02        1232 usr/lib/pkgconfig/icu-i18n.pc
    2023-08-03 01:02        1224 usr/lib/pkgconfig/icu-io.pc
    2023-08-03 01:02        1256 usr/lib/pkgconfig/icu-uc.pc

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Anyways, PR most likely needs a build_machine.system() != 'windows' conditional to work around Windows.