package/libunwind: enable on riscv 64-bit glibc
Since upstream commit [1], first included in version 1.6.0,
libunwind supports 64-bit riscv, at least with glibc.
[1] https://github.com/libunwind/libunwind/commit/abd15da8afb35b92ed0cb2c47f6564775b976c24
Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev@mobileye.com>
[Julien: add link to upstream commit and fix version in commit log]
Signed-off-by: Julien Olivain <ju.o@free.fr>