MSVC: Fix initialization of RelWithDebInfo shared library link flags (#15385)

Initialize CMAKE_SHARED_LINKER_FLAGS_RELWITHDEBINFO_INIT from the value
of CMAKE_EXE_LINKER_FLAGS_RELWITHDEBINFO_INIT rather than the one for
the DEBUG configuration.  This typo has been present since the logic was
first added in  commit 36db45082e (ENH: fix up several problems with new
stuff, 2002-11-11).

Reported-by: Gunnar Roth <gunnar.roth@gmx.de>
2 files changed