ENH: Made install prefix test case-insensitive on Windows and OSX.

Common/Testing/CMakeLists.txt

@@ -87,7 +87,14 @@ ENDIF(PYTHON_EXECUTABLE)
 # Configure the VTK install test.  It is enabled only if the install
 # prefix is set to an InstallTest directory under the top of the build
 # tree.
-STRING(COMPARE EQUAL "${CMAKE_INSTALL_PREFIX}" "${VTK_BINARY_DIR}/InstallTest"
+IF(WIN32 OR APPLE)
+  STRING(TOLOWER "${CMAKE_INSTALL_PREFIX}" VTK_TEST_INSTALL_LEFT)
+  STRING(TOLOWER "${VTK_BINARY_DIR}/InstallTest" VTK_TEST_INSTALL_RIGHT)
+ELSE(WIN32 OR APPLE)
+  SET(VTK_TEST_INSTALL_LEFT "${CMAKE_INSTALL_PREFIX}")
+  SET(VTK_TEST_INSTALL_RIGHT "${VTK_BINARY_DIR}/InstallTest")
+ENDIF(WIN32 OR APPLE)
+STRING(COMPARE EQUAL "${VTK_TEST_INSTALL_LEFT}" "${VTK_TEST_INSTALL_RIGHT}"
   VTK_TEST_INSTALL)
 
 # No install when using rpaths.