Update the remaining references to sys_string_conversions.h to its new location.

crypto/cssm_init.cc

Index: crypto/cssm_init.cc
diff --git a/crypto/cssm_init.cc b/crypto/cssm_init.cc
index cf5ac258ca7f3e21cca5dcee55a8941daa764de9..7b7e52dc5e0d47e9d8caeaa040a312b6254f03aa 100644
--- a/crypto/cssm_init.cc
+++ b/crypto/cssm_init.cc
@@ -9,7 +9,7 @@
 #include "base/logging.h"
 #include "base/mac/scoped_cftyperef.h"
 #include "base/memory/singleton.h"
-#include "base/sys_string_conversions.h"
+#include "base/strings/sys_string_conversions.h"
 
 // When writing crypto code for Mac OS X, you may find the following
 // documentation useful: