FindGSL.cmake shipped with current CMake is messed up, back to our own

CMakeModules/FindGSL.cmake

+#
+# Find GSL includes and library
+#
+# FindGSL() shipped with CMake is somehow broken in newer versions (>= 3.9,
+# maybe also 3.7 and 3.8). It works only if GSL_ROOT_DIR is set. Hints do
+# not work.
+#
+# :FIXME: For the time being we use our own version.
+#
+# GSL_INCLUDE_DIR - where to find ippl.h
+# GSL_LIBRARY     - GSL library to link against.
+# GSL_CBLAS_LIBRARY - GSL CBlas library to link against
+# GSL_FOUND       - do not attempt to use if "no" or undefined.
+
+FIND_PATH (GSL_INCLUDE_DIR gsl/gsl_fft.h
+    HINTS $ENV{GSL_INCLUDE_PATH} $ENV{GSL_INCLUDE_DIR} $ENV{GSL_PREFIX}/include $ENV{GSL_DIR}/include $ENV{GSL}/include
+    PATHS ENV CPP_INCLUDE_PATH
+)
+
+
+FIND_LIBRARY (GSL_LIBRARY gsl
+    HINTS $ENV{GSL_LIBRARY_PATH} $ENV{GSL_LIBRARY_DIR} $ENV{GSL_PREFIX}/lib $ENV{GSL_DIR}/lib $ENV{GSL}/lib
+    PATHS ENV LIBRARY_PATH
+)
+
+FIND_LIBRARY (GSL_CBLAS_LIBRARY gslcblas
+    HINTS $ENV{GSL_LIBRARY_PATH} $ENV{GSL_LIBRARY_DIR} $ENV{GSL_PREFIX}/lib $ENV{GSL_DIR}/lib $ENV{GSL}/lib
+    PATHS ENV LIBRARY_PATH
+)
+
+IF (GSL_INCLUDE_DIR AND GSL_LIBRARY)
+    SET( GSL_FOUND "YES" )
+ENDIF()
+
+IF (GSL_FOUND)
+   IF (NOT GSL_FIND_QUIETLY)
+      MESSAGE(STATUS "Found GSL libraries: ${GSL_LIBRARY}")
+      MESSAGE(STATUS "Found GSL include dir: ${GSL_INCLUDE_DIR}")
+   ENDIF (NOT GSL_FIND_QUIETLY)
+ELSE ()
+   IF (GSL_FIND_REQUIRED)
+      MESSAGE(FATAL_ERROR "Could not find GSL!")
+   ENDIF ()
+ENDIF ()