Build: changes needed to build on FreeBSD

* Fix SDL not finding Xlib.h
* Link to clangSupport library for newer LLVM versions
* Add FreeBSD essential symbols to symbols_unix.map

Pull Request: https://projects.blender.org/blender/blender/pulls/105892

build_files/cmake/Modules/FindClang.cmake

@@ -80,6 +80,7 @@ set(_CLANG_FIND_COMPONENTS
   clangAST
   clangLex
   clangBasic
+  clangSupport
 )
 
 set(_CLANG_LIBRARIES)
@@ -94,7 +95,9 @@ foreach(COMPONENT ${_CLANG_FIND_COMPONENTS})
     PATH_SUFFIXES
       lib64 lib
     )
-  list(APPEND _CLANG_LIBRARIES "${CLANG_${UPPERCOMPONENT}_LIBRARY}")
+  if(CLANG_${UPPERCOMPONENT}_LIBRARY)
+    list(APPEND _CLANG_LIBRARIES "${CLANG_${UPPERCOMPONENT}_LIBRARY}")
+  endif()
 endforeach()
 
 

extern/sdlew/CMakeLists.txt

@@ -7,7 +7,7 @@ set(INC
 )
 
 set(INC_SYS
-
+ ${X11_X11_INCLUDE_PATH}
 )
 
 set(SRC

source/creator/symbols_unix.map

@@ -39,6 +39,9 @@ global:
   realpath;
   sched_*;
   valloc;
+  /* needed on FreeBSD */
+  __progname;
+  environ;
 local:
   *;
 };