For applications that set VERSION the installation targets of pdb
files were wrong in qmake's nmake Makefile generator.
Replace code that tries to reconstruct that target's versioned
extension with TARGET_EXT which already contains the fully resolved
target extension.
Fixes: QTBUG-74265
Change-Id: I9553a5f70170e077a59c866079ae51647ae80bef
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>