Any but the last /MERGE:from=to option passed to QMAKE_LFLAGS was
ignored. Now, the first options gets a <MergeSections> tag and all
further options are added as AdditionalOptions, because vcxproj files /
the VS property editor do not support multiple MergeSections entries.
Pick-to: 5.15
Fixes: QTBUG-86062
Change-Id: I65bddf0b8c7ed6c162008d6ad1b58c2aba2d07d9
Reviewed-by: Kai Koehne <kai.koehne@qt.io>