[pion-net] fix rebuild on F18+

[jvcelak]

commit ff29eab1e753bc9f906d415408b2f6ccfa5849b5
Author: Jan Vcelak <jvcelak at redhat.com>
Date:   Mon Aug 13 15:46:25 2012 +0200

    fix rebuild on F18+

 pion-net.spec |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/pion-net.spec b/pion-net.spec
index 1ff4874..9cca747 100644
--- a/pion-net.spec
+++ b/pion-net.spec
@@ -45,6 +45,10 @@ This package contains Doxygen HTML documentation for pion-net library.
 
 
 %build
+
+# fix build on Fedora 18
+export LD_FLAGS="%{__global_ldflags} -lboost_system-mt"
+
 ./autogen.sh
 %configure \
 	--with-plugins=%{_libdir}/pion/plugins \