package/gcc: nios2 Backport nios2 r31 fix

package/gcc: nios2 Backport nios2 r31 fix

As reported on the mailing list, gcc5 with binutils 2.26.1 produce some
assembler error "r31 cannot be used with jmp; use ret instead" [1]

The bug is reported upstream [2], but gcc 5.4 needs an upstream patch to
fix this issue.

Note: openembedded backported the same patch for gcc 5.3 [3]

Fixes:

alsa-lib:
http://autobuild.buildroot.net/results/1fc9806a62b813b085c39d36000f4d9d18f779df
http://autobuild.buildroot.net/results/03eb11b6a783da1985c19858f6c5f69027e0ed9c
http://autobuild.buildroot.net/results/d620812ae79c4e8252d2b0c410f94e9cdcbcfbc3
http://autobuild.buildroot.net/results/04b7609f5decc71bf25e981f14756029715fc621
http://autobuild.buildroot.net/results/e85be7ffd62e7ab95c4dd0049b0c67ae98f75543

freeswitch:
http://autobuild.buildroot.net/results/96f69b7be1978f85271e2827c2e18d4ed8de8dfc

flac:
http://autobuild.buildroot.net/results/fb3/fb36a9939cac82dc187b64fae93720ea1930f343

libmodplug:
http://autobuild.buildroot.net/results/f12/f12a5d5b4f5338438fbb053ec013e69559eaaa0c

[1] http://lists.busybox.net/pipermail/buildroot/2016-September/172932.html
[2] https://sourceware.org/bugzilla/show_bug.cgi?id=20674
[3] http://lists.openembedded.org/pipermail/openembedded-core/2016-February/117633.html

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>