package/rtorrent: requires gcc >= 4.9

package/rtorrent: requires gcc >= 4.9

Upstream considers the build error as compiler bug:
https://github.com/rakshasa/rtorrent/issues/223

Building with gcc 4.9 works, tested with this defconfig:

BR2_TOOLCHAIN_BUILDROOT_WCHAR=y
BR2_GCC_VERSION_4_9_X=y
BR2_TOOLCHAIN_BUILDROOT_CXX=y
BR2_PACKAGE_RTORRENT=y

Fixes
http://autobuild.buildroot.net/results/990/990c9d62f3d275bd4e2ffad41bdb6d68c483cbb1/

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>