Merge branch 'wdconinc-master-patch-41662' into 'master'

find_package nanocernlib before using internal

See merge request eic/mceg/pythia6m!1

CMakeLists.txt

@@ -31,8 +31,14 @@ add_subdirectory(pythia6m/radiator)
 add_subdirectory(pythia6m/radgen)
 add_subdirectory(pythia6m/pythia6)
 
-add_subdirectory(nanocernlib)
-
+find_package(nanocernlib)
+if(NOT ${nanocernlib_LIBRARIES})
+  message(STATUS "Using internal nanocernlib")
+  add_subdirectory(nanocernlib)
+else()
+  message(STATUS "Using nanocernlib at ${NANOCERNLIB_INCLUDE_DIR}")
+endif()
+ 
 add_subdirectory(program)
 
 ################################################################################