libsigsegv: fix sparc64 compile

Compile tested for sparc/glibc and sparc64/glibc.
Fixes following autobuilder problem:
http://autobuild.buildroot.net/results/1d8e0c22594aef53f7a4de3491454aa78311c815/



Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>