quazip: fix leaked cross sysroot path in cmake exports

[omemoji]

Cross-built quazip packages (e.g. aarch64) ship CMake exports that still contain the cross sysroot path:

INTERFACE_LINK_LIBRARIES "Qt6::Core;Qt6::Core5Compat;ZLIB::ZLIB;/usr/aarch64-linux-gnu/usr/lib/libbz2.so"

This affects both QuaZip-Qt5_SharedTargets.cmake and QuaZip-Qt6_SharedTargets.cmake. Any native build that consumes these exports fails at link time:

ninja: error: '/usr/aarch64-linux-gnu/usr/lib/libbz2.so', needed by '...', missing and no known rule to make it

x86_64 is not affected because it is built natively.

Changes:

• strip ${XBPS_CROSS_BASE} from the Qt5/Qt6 *_SharedTargets.cmake in post_install (cross builds only)
• add bzip2-devel to makedepends: quazip links against bzip2, but it was never declared
• add bzip2-devel to depends of quazip-devel and quazip-qt6-devel, since the exports reference /usr/lib/libbz2.so

Testing the changes

• I tested the changes in this PR: YES
  • Applied the substitution to the currently distributed aarch64 quazip-devel / quazip-qt6-devel exports; both now point to /usr/lib/libbz2.so.

Local build testing

• I built this PR locally for my native architecture, (aarch64-glibc)
• Cross builds: armv7l-glibc (others relying on CI.)