unnecessary include brings in boost headers that are broken under rhel-7

Change-Id: I1ad477b9db9ba960ae2c417799e5d91b63538d57
(cherry picked from commit 12fc5b85)

external/liborcus/UnpackedTarball_liborcus.mk

@@ -17,6 +17,7 @@ $(eval $(call gb_UnpackedTarball_add_patches,liborcus,\
 	external/liborcus/0001-workaround-a-linking-problem-on-windows.patch \
 	external/liborcus/rpath.patch.0 \
 	external/liborcus/fix-crash-ooo55043-1.patch.0 \
+	external/liborcus/unusedheader.patch.0 \
 ))
 
 # vim: set noet sw=4 ts=4:

external/liborcus/unusedheader.patch.0

+--- ./src/parser/pstring.cpp.orig	2015-12-02 14:38:44.658744408 +0000
++++ ./src/parser/pstring.cpp	2015-12-02 14:38:50.449658497 +0000
+@@ -13,8 +13,6 @@
+ #include <iostream>
+ #include <vector>
+ 
+-#include <boost/thread/mutex.hpp>
+-
+ using namespace std;
+ 
+ namespace orcus {