Fix problem with missing ROOTSYS variable

If using a non FairSoft installation of the dependencies problems were
reported after the last changes to the build system. Instead of hardcoding
the SIMPATH use the the information from ROOT about its binary directory.
Remove some old usage of the root-config script, use CMake variables provided
by ROOT instead.

CMakeLists.txt

@@ -71,8 +71,9 @@ list(PREPEND CMAKE_PREFIX_PATH ${SIMPATH})
 find_package(ROOT 6.22 CONFIG REQUIRED)
 if(ROOT_FOUND)
   Message("Root was found")
-  set(ROOT_CINT_EXECUTABLE ${SIMPATH}/bin/rootcling)
-  set(ROOT_CONFIG_EXECUTABLE ${SIMPATH}/bin/root-config)
+  # The following CMake variables are needed until the modernization is done 
+  set(ROOT_CINT_EXECUTABLE ${ROOT_BINDIR}/rootcling)
+  set(ROOT_CONFIG_EXECUTABLE ${ROOT_BINDIR}/root-config)
   set(ROOT_INCLUDE_DIR ${ROOT_INCLUDE_DIRS})
 endif()
 

core/CMakeLists.txt

@@ -14,13 +14,8 @@ add_subdirectory(detectors/tof)
 add_subdirectory(detectors/sts)
 add_subdirectory(detectors/psd)
 
-Execute_Process(COMMAND ${ROOT_CONFIG_EXECUTABLE} --has-opengl
-                OUTPUT_VARIABLE EveIsBuild
-                OUTPUT_STRIP_TRAILING_WHITESPACE
-               )
-
-If(${EveIsBuild} STREQUAL yes)
-  Message(STATUS "Build the eventdisplay.")
+If(ROOT_opengl_FOUND)
+  Message(STATUS "OpenGL support found. Build the eventdisplay.")
   add_subdirectory (eventdisplay)
 Else()
   Message(STATUS "The eventdisplay is not build, there is no OpenGL support.")