Merge topic 'cygwin-patches'

ecc1961768 FindTclsh: Drop Cygwin-specific behavior and use POSIX code path
af666acdf4 FindOpenGL: Drop Cygwin-specific behavior and use POSIX code path
8edbc59e46 install: Use case-sensitive pattern matching on Cygwin
24482499ea FindPerlLibs: Add versioned perl library name for Cygwin

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !5092