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>

package/rtorrent/Config.in

@@ -4,6 +4,8 @@ config BR2_PACKAGE_RTORRENT
 	depends on BR2_USE_WCHAR
 	depends on BR2_TOOLCHAIN_HAS_THREADS
 	depends on BR2_USE_MMU # fork()
+	# gcc < 4.9 cause an "internal compiler error"
+	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_9
 	depends on BR2_TOOLCHAIN_HAS_SYNC_1 && BR2_TOOLCHAIN_HAS_SYNC_4
 	select BR2_PACKAGE_LIBCURL
 	select BR2_PACKAGE_LIBTORRENT
@@ -14,7 +16,8 @@ config BR2_PACKAGE_RTORRENT
 
 	  https://github.com/rakshasa/rtorrent
 
-comment "rtorrent needs a toolchain w/ C++, threads, wchar"
+comment "rtorrent needs a toolchain w/ C++, threads, wchar, gcc >= 4.9"
 	depends on BR2_USE_MMU
 	depends on BR2_TOOLCHAIN_HAS_SYNC_1 && BR2_TOOLCHAIN_HAS_SYNC_4
-	depends on !(BR2_INSTALL_LIBSTDCPP && BR2_USE_WCHAR && BR2_TOOLCHAIN_HAS_THREADS)
+	depends on !(BR2_INSTALL_LIBSTDCPP && BR2_USE_WCHAR && \
+		BR2_TOOLCHAIN_HAS_THREADS && BR2_TOOLCHAIN_GCC_AT_LEAST_4_9)