qt5base: unconditionally install network, sql, xml and test modules to target

The qt5 build system currently unconditionally builds and installs into
staging these libraries, so ensure they also get installed into target to
make sure we don't end up with dynamic linker errors at runtime.

From src.pro:

SUBDIRS += src_network src_sql src_xml src_testlib

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>