tools lib symbol: Use -D_FORTIFY_SOURCE=2 for non-debug builds

tools lib symbol: Use -D_FORTIFY_SOURCE=2 for non-debug builds

Forwarded: https://lore.kernel.org/all/20230424102827.58707-1-ukleinek@debian.org/

Commit 160be157eaba ("tool lib symbol: Add Makefile/Build") failed to
define _FORTIFY_SOURCE to 2, probabaly this was cut&pasted from other
Makefiles with the same problem.

Fixes: 160be157eaba ("tool lib symbol: Add Makefile/Build")
Signed-off-by: Uwe Kleine-König <ukleinek@debian.org>
Acked-by: Ian Rogers <irogers@google.com>
Gbp-Pq: Topic bugfix/all
Gbp-Pq: Name tools_lib_symbol_use_d_fortify_source_2_for_non_debug_builds.patch