Glob: Use case-sensitive globbing on Cygwin

Based on downstream patch from Cygwin package for CMake by Marco Atzeri:

* https://github.com/matzeri/cygwin-pkg/blob/64864eb8f0d635ea44226e4b9a41a7ca59a1c7dd/cmake/3.17.3-case-sensitivity.patch

Glob.cxx

@@ -27,7 +27,7 @@
 #include <cstdio>
 #include <cstring>
 namespace KWSYS_NAMESPACE {
-#if defined(_WIN32) || defined(__APPLE__) || defined(__CYGWIN__)
+#if defined(_WIN32) || defined(__APPLE__)
 // On Windows and Apple, no difference between lower and upper case
 #  define KWSYS_GLOB_CASE_INDEPENDENT
 #endif