Fixed Symbian include header case sensitivity (thanks Alfred E. Heggestad)

git-svn-id: https://svn.pjsip.org/repos/pjproject/trunk@1688 74dad513-b988-da41-8d7b-12977e46ad98
diff --git a/pjsip-apps/src/symbian_ua/ua.cpp b/pjsip-apps/src/symbian_ua/ua.cpp
index d2e00b1..3e33ca4 100644
--- a/pjsip-apps/src/symbian_ua/ua.cpp
+++ b/pjsip-apps/src/symbian_ua/ua.cpp
@@ -652,7 +652,7 @@
 #endif
 
 
-#include <ES_SOCK.H>
+#include <es_sock.h>
 
 ////////////////////////////////////////////////////////////////////////////
 int ua_main()