SuperBuild: prefer using dfalt and mfhdfalt as GDAL checks them first (conflict with system dfalt)

SuperBuild/CMake/External_hdf4.cmake

@@ -27,8 +27,8 @@ ADDTO_DEPENDENCIES_IF_NOT_SYSTEM(HDF4 ZLIB JPEG)
 
 set(HDF4_SB_CONFIG)
 
-set(HDF4_SB_DF_LIB df)
-set(HDF4_SB_MF_LIB mfhdf)
+set(HDF4_SB_DF_LIB dfalt)
+set(HDF4_SB_MF_LIB mfhdfalt)
 
 ExternalProject_Add(HDF4
   PREFIX HDF4

SuperBuild/CMake/External_netcdf.cmake

@@ -73,3 +73,5 @@ ExternalProject_Add(NETCDF
   LOG_BUILD 1
   LOG_INSTALL 1
   )
+
+SUPERBUILD_PATCH_SOURCE(NETCDF)

SuperBuild/patches/NETCDF/netcdf-1-hdfAlt-all.diff

+diff -burN netcdf-4.4.1.1-orig/CMakeLists.txt netcdf-4.4.1.1/CMakeLists.txt
+--- netcdf-4.4.1.1-orig/CMakeLists.txt	2017-09-18 19:22:31.832817084 +0200
++++ netcdf-4.4.1.1/CMakeLists.txt	2017-09-18 19:23:32.001343319 +0200
+@@ -434,12 +434,12 @@
+     INCLUDE_DIRECTORIES(${MFHDF_H_INCLUDE_DIR})
+   ENDIF()
+ 
+-  FIND_LIBRARY(HDF4_DF_LIB NAMES df libdf hdf)
++  FIND_LIBRARY(HDF4_DF_LIB NAMES dfalt df libdf hdf)
+   IF(NOT HDF4_DF_LIB)
+     MESSAGE(FATAL_ERROR "Can't find or link to the hdf4 df library.")
+   ENDIF()
+ 
+-  FIND_LIBRARY(HDF4_MFHDF_LIB NAMES mfhdf libmfhdf)
++  FIND_LIBRARY(HDF4_MFHDF_LIB NAMES mfhdfalt mfhdf libmfhdf)
+   IF(NOT HDF4_MFHDF_LIB)
+     MESSAGE(FATAL_ERROR "Can't find or link to the hdf4 mfhdf library.")
+   ENDIF()