perf build: Avoid defining _FORTIFY_SOURCE multiple times

One in perf's CFLAGS and the other in the distro python binding
scripts.

So if use the usual technique of first -D_FORTIFY_SOURCE then -D it.

Noticed with:

opensuse tumbleweed:

  gcc version 12.1.1 20220629 [revision 7811663964aa7e31c3939b859bbfa2e16919639f] (SUSE Linux)

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>