toolchain-external: CodeSourcery NiosII 2015.11 affected by PR19405

See bug report https://sourceware.org/bugzilla/show_bug.cgi?id=19405

Fixes:
http://autobuild.buildroot.net/results/ee562524c5b12191e584ceae89006c5a5103e700



Signed-off-by: Romain Naour <romain.naour@gmail.com>
[Thomas:
 - rename BR2_TOOLCHAIN_BINUTILS_HAS_BUG_19405 to
   BR2_TOOLCHAIN_HAS_BINUTILS_BUG_19405
 - propagate to the qwt package, which is now selecting
   BR2_PACKAGE_QT_GUI_MODULE.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>