Fix warning in PoolAlloc.cpp.

Use "I" instead of "l" as printf type prefix for size_t.
Review URL: https://codereview.appspot.com/5572071

git-svn-id: https://angleproject.googlecode.com/svn/trunk@966 736b8ea6-26fd-11df-bfd4-992fa37f6226
diff --git a/src/compiler/PoolAlloc.cpp b/src/compiler/PoolAlloc.cpp
index e286c7d..4956ef7 100644
--- a/src/compiler/PoolAlloc.cpp
+++ b/src/compiler/PoolAlloc.cpp
@@ -157,7 +157,7 @@
             char assertMsg[80];
 
             // We don't print the assert message.  It's here just to be helpful.
-            sprintf(assertMsg, "PoolAlloc: Damage %s %lu byte allocation at 0x%p\n",
+            sprintf(assertMsg, "PoolAlloc: Damage %s %Iu byte allocation at 0x%p\n",
                     locText, size, data());
             assert(0 && "PoolAlloc: Damage in guard block");
         }