configure: Fix the msvcrt version check for mingw32

This was actually broken when committed in 46e3936fb04; the
test never succeeded, and thus, _aligned_malloc wasn't actually
used on legacy mingw.

Signed-off-by: Martin Storsjö <martin@martin.st>
(cherry picked from commit 427f7a1f9ec1977bcb57cb4d6e6f7228dc1e858b)
