Incorporate RalphAS's fix for translations units being dropped from…

… custom system images.

contrib/build_sysimg.jl

@@ -162,16 +162,12 @@ function link_sysimg(sysimg_path=nothing, cc=find_system_compiler(), debug=false
     end
 
     sysimg_file = "$sysimg_path.$(Libdl.dlext)"
-    info("Linking sys.$(Libdl.dlext)")
-    info("$cc $(join(FLAGS, ' ')) -o $sysimg_file $sysimg_path.o")
+    cc_cmd = `$cc $FLAGS -o $sysimg_path.tmp -Wl,--whole-archive $sysimg_path.o -Wl,--no-whole-archive`
+    @info("Linking sys.$(Libdl.dlext) with $cc_cmd")
     # Windows has difficulties overwriting a file in use so we first link to a temp file
-    if Sys.iswindows() && isfile(sysimg_file)
-        if success(pipeline(`$cc $FLAGS -o $sysimg_path.tmp $sysimg_path.o`; stdout=stdout, stderr=stderr))
-            mv(sysimg_file, "$sysimg_file.old"; force=true)
-            mv("$sysimg_path.tmp", sysimg_file; force=true)
-        end
-    else
-        run(`$cc $FLAGS -o $sysimg_file $sysimg_path.o`)
+    if success(pipeline(cc_cmd; stdout=stdout, stderr=stderr))
+        mv(sysimg_file, "$sysimg_file.old"; force=true)
+        mv("$sysimg_path.tmp", sysimg_file; force=true)
     end
     @info("System image successfully built at $sysimg_path.$(Libdl.dlext)")
     return