add sysimage size to make output report

Author: IanButterworth

contrib/generate_precompile.jl

@@ -453,6 +453,8 @@ let pre_output_time = time_ns()
     # Print report after sysimage has been saved so all time spent can be captured
     Base.postoutput() do
         output_time = time_ns() - pre_output_time
-        print("Output ────── "); Base.time_print(output_time); println()
+        print("Output ────── ")
+        Base.time_print(output_time)
+        println(" (sysimage size: ", Base.format_bytes(filesize(unsafe_string(Base.JLOptions().outputo))), ")")
     end
 end