Accept flex > 2.5.x on Windows, too.
Accept flex > 2.5.x on Windows, too.

Commit 32f15d05c fixed this in configure, but missed the similar check
in the MSVC scripts.

Michael Paquier, per report from Victor Wagner

zeroae/postgres-xl,zeroae/postgres-xl,zeroae/postgres-xl,zeroae/postgres-xl,zeroae/postgres-xl