Add VDT to default ROOT_INCLUDE_PATH if builtin is set to off

Author: LukasBreitwieser

CMakeLists.txt

@@ -567,6 +567,7 @@ if(runtime_cxxmodules)
                                 ROOTIGNOREPREFIX=1 ROOT_HIST=0 $<TARGET_FILE:root.exe> -l -q -b)
   else()
     set(modules_idx_cmd COMMAND ${ld_library_path}=${library_output_dir}:$ENV{${ld_library_path}}
+                                ROOT_INCLUDE_PATH=${DEFAULT_ROOT_INCLUDE_PATH}
                                 ROOTIGNOREPREFIX=1 ROOT_HIST=0 $<TARGET_FILE:root.exe> -l -q -b)
   endif()
   add_custom_command(OUTPUT ${library_output_dir}/modules.idx
@@ -591,6 +592,7 @@ if(WIN32)
                           ROOTIGNOREPREFIX=1 ROOT_HIST=0 $<TARGET_FILE:root.exe> -l -q -b -n -x ${CMAKE_SOURCE_DIR}/tutorials/hsimple.C -e return)
 else()
   set(hsimple_cmd COMMAND ROOT_INCLUDE_PATH="${DEFAULT_ROOT_INCLUDE_PATH}" ${ld_library_path}=${CMAKE_LIBRARY_OUTPUT_DIRECTORY}:$ENV{${ld_library_path}}
+                          ROOT_INCLUDE_PATH=${DEFAULT_ROOT_INCLUDE_PATH}
                           ROOTIGNOREPREFIX=1 ROOT_HIST=0 $<TARGET_FILE:root.exe> -l -q -b -n -x ${CMAKE_SOURCE_DIR}/tutorials/hsimple.C -e return)
 endif()
 add_custom_command(OUTPUT tutorials/hsimple.root

cmake/modules/SearchInstalledSoftware.cmake

@@ -1617,6 +1617,8 @@ if(vdt OR builtin_vdt)
     install(DIRECTORY ${CMAKE_BINARY_DIR}/include/vdt
             DESTINATION ${CMAKE_INSTALL_INCLUDEDIR} COMPONENT extra-headers)
     set_property(GLOBAL APPEND PROPERTY ROOT_BUILTIN_TARGETS VDT::VDT)
+  else()
+    BUILD_ROOT_INCLUDE_PATH("${VDT_INCLUDE_DIR}")
   endif()
 endif()