[CTest] Added check for DIFF_DATA length.

On Windows the maximum cmd length is 8192 chars.

scripts/cmake/test/AddTest.cmake

@@ -112,6 +112,13 @@ function (AddTest)
         return()
     endif()
 
+    if(AddTest_DIFF_DATA)
+        string(LENGTH "${AddTest_DIFF_DATA}" DIFF_DATA_LENGTH)
+        if(${DIFF_DATA_LENGTH} GREATER 7500)
+            message(FATAL_ERROR "${AddTest_NAME}: DIFF_DATA to long! Consider using regex-syntax: TODO")
+        endif()
+    endif()
+
     if((AddTest_TESTER STREQUAL "diff" OR AddTest_TESTER STREQUAL "vtkdiff") AND NOT AddTest_DIFF_DATA)
         message(FATAL_ERROR "AddTest(): ${AddTest_NAME} - no DIFF_DATA given!")
     endif()
@@ -130,7 +137,6 @@ function (AddTest)
                 ${TESTER_ARGS} ${AddTest_SOURCE_PATH}/${FILE_EXPECTED} \
                 ${AddTest_BINARY_PATH}/${FILE}")
         endforeach()
-        string(REPLACE ";" " && " TESTER_COMMAND "${TESTER_COMMAND}")
     elseif(AddTest_TESTER STREQUAL "vtkdiff")
         list(LENGTH AddTest_DIFF_DATA DiffDataLength)
         math(EXPR DiffDataLengthMod4 "${DiffDataLength} % 4")