Source: Gentoo
Upstream: unknown
Reason: fixes underlinking

--- CMakeLists.txt
+++ CMakeLists.txt
@@ -392,7 +392,7 @@
         message(FATAL_ERROR "Unix port requires pthreads support.")
     endif()
     set(ALLEGRO_HAVE_LIBPTHREAD 1)
-    list(APPEND PLATFORM_LIBS m ${CMAKE_THREAD_LIBS_INIT})
+    list(APPEND PLATFORM_LIBS dl m ${CMAKE_THREAD_LIBS_INIT})
     list(APPEND PLATFORM_SOURCES ${ALLEGRO_SRC_UNIX_FILES})
 
     if(WANT_OSS)