This is required when passing --without-libnotify because otherwise the first call to
PKG_CHECK_MODULES is not called and the ./configure will bail out.

http://bugs.gentoo.org/435586
http://code.google.com/p/transmission-remote-gtk/issues/detail?id=216

--- configure.ac
+++ configure.ac
@@ -34,6 +34,7 @@
 AC_PROG_INSTALL
 LT_INIT
 IT_PROG_INTLTOOL([0.35.0])
+PKG_PROG_PKG_CONFIG
 
 AC_CHECK_HEADERS([stdlib.h string.h])
 AC_TYPE_SIZE_T