Fix OS/2 tinderbox bustage (PR_CALLBACK). r=disttsc@bart.nl

netwerk/cache/src/nsDiskCacheDevice.cpp

@@ -1510,7 +1510,8 @@ nsresult nsDiskCacheDevice::clobberDiskCache()
 }
 
 
-static int compareRecords(const void* e1, const void* e2, void* /*unused*/)
+PR_STATIC_CALLBACK(int)
+compareRecords(const void* e1, const void* e2, void* /*unused*/)
 {
     const nsDiskCacheRecord* r1 = (const nsDiskCacheRecord*) e1;
     const nsDiskCacheRecord* r2 = (const nsDiskCacheRecord*) e2;