...even if they are modified for the remaineder of configure.ac itself in the
MSVC 2015-specific code checking for UCRT.  Otherwise, the flags determined by
LinkTarget.mk would lack any debug and optimization flags when building with
MSVC 2015.

Change-Id: Ib78418e0ad04bf2eae16a14b5c0904ba4f582eca
Reviewed-on: https://gerrit.libreoffice.org/34248Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>