debug/gdb: fix from upstream with newer glibc(siginfo vs siginfo_t, Gentoo gdb-7.4.1 patch)

This is for when you failed to build gdb-native with the error:

gdb-7.4.1/gdb/linux-nat.h:79:18: error: field 'siginfo' has incomplete type"

This is from mirror://gentoo/distfiles/gdb-7.4.1-patches-2.tar.xz

Signed-off-by: "Jang, Bongseo" <graycells@gmail.com>
[yann.morin.1998@free.fr: refresh ptrace_setsiginfo patch]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Message-ID: <4eef2edec3201c50b420.1348370891@localhost.localdomain>
PatchWork-ID: 186179

 # Compute s390-specific values

 CT_DoArchTupleValues() {

     # That's the only thing to override

     if [ "${CT_ARCH_64}" = "y" ]; then

         CT_TARGET_ARCH="s390x"

     fi

 }