From: =?utf-8?q?Timo_R=C3=B6hling?= <roehling@debian.org>
Date: Mon, 18 Oct 2021 16:45:01 +0200
Subject: Make FindFLTK safe to include multiple times

Forwarded: not-needed

This is a backport of commit 51fd21736b10e2fa04382c5aa71f2044d31e362f
from the 3.22.x milestone.
---
 Modules/FindFLTK.cmake | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/Modules/FindFLTK.cmake b/Modules/FindFLTK.cmake
index bab7256..d54d2f6 100644
--- a/Modules/FindFLTK.cmake
+++ b/Modules/FindFLTK.cmake
@@ -152,13 +152,17 @@ if(NOT FLTK_DIR)
 endif()
 
 # Check if FLTK was built using CMake
-if(EXISTS ${FLTK_DIR}/FLTKConfig.cmake)
-  set(FLTK_BUILT_WITH_CMAKE 1)
-endif()
+foreach(fltk_include IN LISTS FLTK_DIR)
+  if(EXISTS "${fltk_include}/FLTKConfig.cmake")
+    set(FLTK_BUILT_WITH_CMAKE 1)
+    set(FLTK_CMAKE_PATH "${fltk_include}/FLTKConfig.cmake")
+    break()
+  endif()
+endforeach()
 
 if(FLTK_BUILT_WITH_CMAKE)
   set(FLTK_FOUND 1)
-  include(${FLTK_DIR}/FLTKConfig.cmake)
+  include("${FLTK_CMAKE_PATH}")
 
   # Fluid
   if(FLUID_COMMAND)