[network-manager-openvpn] build: avoid expanding prefix prematurely

[Lubomir Rintel <lkundrak src gnome org>]

commit 0bea0dfcec4faa1e7d28be37067efa7d6095bf67
Author: Lubomir Rintel <lkundrak v3 sk>
Date:   Fri Aug 21 12:25:27 2015 +0200

    build: avoid expanding prefix prematurely
    
    We need to expand it at make time to whatever we use, not NetworkManger itself.

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index f82f8ea..b4ce3e1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -86,7 +86,7 @@ PKG_CHECK_MODULES(LIBNM, libnm >= 1.1.0)
 LIBNM_CFLAGS="$LIBNM_CFLAGS -DNM_VERSION_MIN_REQUIRED=NM_VERSION_1_2"
 LIBNM_CFLAGS="$LIBNM_CFLAGS -DNM_VERSION_MAX_ALLOWED=NM_VERSION_1_2"
 
-NM_VPN_SERVICE_DIR=`$PKG_CONFIG --variable vpnservicedir libnm`
+NM_VPN_SERVICE_DIR=`$PKG_CONFIG pkg-config --define-variable prefix='\${prefix}' --variable vpnservicedir 
libnm`
 AC_SUBST(NM_VPN_SERVICE_DIR)
 
 NM_COMPILER_WARNINGS