CMake: (fix) libaec

Implemented the fallback option for the case if version 1.0.5
of libaec could not be found.

CMakeFilters.cmake

@@ -111,13 +111,16 @@ option (HDF5_ENABLE_SZIP_SUPPORT "Use SZip Filter" OFF)
 if (HDF5_ENABLE_SZIP_SUPPORT)
   option (HDF5_ENABLE_SZIP_ENCODING "Use SZip Encoding" OFF)
   if (NOT SZIP_USE_EXTERNAL)
+    set(SZIP_FOUND FALSE)
     if (USE_LIBAEC)
       set(libaec_USE_STATIC_LIBS ${USE_LIBAEC_STATIC})
       find_package (libaec 1.0.5 CONFIG)
       if (SZIP_FOUND)
         set (LINK_COMP_LIBS ${LINK_COMP_LIBS} ${SZIP_LIBRARIES})
       endif ()
-    else ()
+    endif ()
+
+    if (NOT SZIP_FOUND)
       find_package (SZIP NAMES ${SZIP_PACKAGE_NAME}${HDF_PACKAGE_EXT} COMPONENTS static shared)
       if (NOT SZIP_FOUND)
         find_package (SZIP) # Legacy find