Make sure builtins are built before starting to build ROOT

This is necessary because LLVM depends on ZLIB, for example, and its
build system is such that the dependency is not caught by CMake when
builtin_zlib=ON.

CMakeLists.txt

@@ -305,7 +305,8 @@ file(WRITE "${CMAKE_BINARY_DIR}/include/module.modulemap.extra" "${__modulemap_e
 set(ROOT_CXXMODULES_WRITE_TO_CURRENT_DIR ON)
 
 get_property(__allHeaders GLOBAL PROPERTY ROOT_HEADER_TARGETS)
-add_custom_target(move_headers ALL DEPENDS ${__allHeaders})
+get_property(__allBuiltins GLOBAL PROPERTY ROOT_BUILTIN_TARGETS)
+add_custom_target(move_headers ALL DEPENDS ${__allHeaders} ${__allBuiltins})
 
 #---Global PCH-----------------------------------------------------------------------------------
 get_property(__allTargets GLOBAL PROPERTY ROOT_DICTIONARY_TARGETS)

builtins/lz4/CMakeLists.txt

@@ -44,3 +44,5 @@ add_library(LZ4::LZ4 ALIAS lz4)
 
 set(LZ4_LIBRARY $<TARGET_FILE:lz4> CACHE INTERNAL "")
 set(LZ4_LIBRARIES LZ4::LZ4 CACHE INTERNAL "")
+
+set_property(GLOBAL APPEND PROPERTY ROOT_BUILTIN_TARGETS LZ4::LZ4)

builtins/xxhash/CMakeLists.txt

@@ -24,3 +24,5 @@ add_library(xxHash::xxHash ALIAS xxhash)
 
 set(xxHash_LIBRARY $<TARGET_FILE:xxhash> CACHE INTERNAL "")
 set(xxHash_LIBRARIES xxHash::xxHash CACHE INTERNAL "")
+
+set_property(GLOBAL APPEND PROPERTY ROOT_BUILTIN_TARGETS xxHash::xxHash)

builtins/zlib/CMakeLists.txt

@@ -73,3 +73,5 @@ endif()
 if(DEFINED ZLIB_LIBRARY_RELEASE)
   set(ZLIB_LIBRARY_RELEASE ${ZLIB_LIBRARY} CACHE INTERNAL "")
 endif()
+
+set_property(GLOBAL APPEND PROPERTY ROOT_BUILTIN_TARGETS ZLIB::ZLIB)