Ladybird/CMake: Launch gdb with follow fork mode to debug WebContent

Author: https://github.com/networkException
Commit: fb71dc5141
Pull-request: https://github.com/SerenityOS/serenity/pull/16583
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/awesomekling ✅
Reviewed-by: https://github.com/linusg

Ladybird/CMakeLists.txt

@@ -105,7 +105,7 @@ add_custom_target(run
 )
 
 add_custom_target(debug
-    COMMAND "${CMAKE_COMMAND}" -E env "SERENITY_SOURCE_DIR=${SERENITY_SOURCE_DIR}" gdb "$<TARGET_FILE:ladybird>"
+    COMMAND "${CMAKE_COMMAND}" -E env "SERENITY_SOURCE_DIR=${SERENITY_SOURCE_DIR}" gdb -ex "set follow-fork-mode child" "$<TARGET_FILE:ladybird>"
     USES_TERMINAL
 )