Drop implicit include dirs from per-file HDF5 include property

A system HDF5 reports /usr/include. CMake filters implicit dirs from
target include directories but not from the source-file
INCLUDE_DIRECTORIES property, so -I/usr/include reached the command line
and broke #include_next <math.h> in <cmath> on gcc-toolset.

ApplicationLibCode/CMakeLists.txt

@@ -237,6 +237,12 @@ if(RESINSIGHT_FOUND_HDF5)
     set(RI_HDF5_INCLUDE_DIRS ${RESINSIGHT_HDF5_DIR}/include)
   else()
     set(RI_HDF5_INCLUDE_DIRS ${HDF5_INCLUDE_DIRS})
+    # A system HDF5 reports /usr/include. CMake does not filter implicit dirs
+    # from the source-file property, and an explicit -I/usr/include breaks
+    # #include_next <math.h> in <cmath> on gcc-toolset.
+    list(REMOVE_ITEM RI_HDF5_INCLUDE_DIRS
+         ${CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES}
+    )
   endif() # MSVC
 
   # Only these files (and HDF5_FILES) include HDF5 headers directly, so scope

ApplicationLibCode/UnitTests/CMakeLists.txt

@@ -292,9 +292,14 @@ if(RESINSIGHT_FOUND_HDF5)
                                        ${RESINSIGHT_HDF5_DIR}/include
     )
   else()
+    # Drop implicit dirs such as /usr/include, see ApplicationLibCode.
+    set(RI_HDF5_TEST_INCLUDE_DIRS ${HDF5_INCLUDE_DIRS})
+    list(REMOVE_ITEM RI_HDF5_TEST_INCLUDE_DIRS
+         ${CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES}
+    )
     set_source_files_properties(
       ${RI_HDF5_TEST_FILES} PROPERTIES INCLUDE_DIRECTORIES
-                                       "${HDF5_INCLUDE_DIRS}"
+                                       "${RI_HDF5_TEST_INCLUDE_DIRS}"
     )
   endif()
 endif()