Move -ldl after object files that may need it.

For some reason I couldn't link with GCC on my freshly installed
Ubuntu 18.04 machine without reordering like this.

Change-Id: I4c68584e1c0996985246f0d15cf2b538781c0fb0
Reviewed-on: https://skia-review.googlesource.com/135866
Auto-Submit: Mike Klein <mtklein@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>
diff --git a/build/common b/build/common
index 86f4558..2752a4a 100644
--- a/build/common
+++ b/build/common
@@ -9,7 +9,7 @@
     description = compile $out
 
 rule link
-    command = $disabled && touch $out || $cc $ldflags $extra_ldflags -ldl -pthread $in -o $out
+    command = $disabled && touch $out || $cc $ldflags $extra_ldflags $in -ldl -pthread -o $out
     description = link $out
 
 include build/targets