1. Don't reassign different versions to same symbol
2. Define symbols used
This fixes warnings with LLD linker (or errors if -Wl,--fatal-warnings is added by toolchain e.g. with Android NDK)
3. Add -Wl,--version-script to CMAKE_REQUIRED_LINK_OPTIONS instead of CMAKE_REQUIRED_FLAGS to prevent unused argument warning in compilation phase
(there is no need for _SAVE variable because we are inside a function and our CMAKE_REQUIRED_LINK_OPTIONS won't escase its scope)
4. Fix removal of version script file (incorrect file name was used)
Pick-to: 6.2 6.5
Task-number: QTBUG-111514
Change-Id: I0a1548c4268ad511760a0d4aa69ba7a0bdcbb0bc
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
d68dbd8b7d