memory: add attributes to memalign for compatibility with glibc 2.35
memory: add attributes to memalign for compatibility with glibc 2.35

glibc 2.35 added the alloc_align attribute to memalign(), and so
our implementation doesn't build against its headers.

Fix by adding the attributes, guarded with a version check.

Test: https://app.circleci.com/pipelines/github/avikivity/seastar?branch=memalign-attribute-glibc-2.35&filter=all
Message-Id: <372303b940e932c8e77a84e6c3bdc0ff05060c55@scylladb.com>

avikivity/seastar,avikivity/seastar,scylladb/seastar,syuu1228/seastar,scylladb/seastar,scylladb/seastar,avikivity/seastar,syuu1228/seastar,syuu1228/seastar