Add linux-x86-latomic target

CLA: trivial

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Todd Short <todd.short@me.com>
(Merged from https://github.com/openssl/openssl/pull/21590)

Configurations/10-main.conf

@@ -861,6 +861,10 @@ my %targets = (
         asm_arch         => 'x86',
         perlasm_scheme   => "elf",
     },
+    "linux-x86-latomic" => {
+        inherit_from     => [ "linux-x86" ],
+        ex_libs          => add(threads("-latomic")),
+    },
     "linux-x86-clang" => {
         inherit_from     => [ "linux-x86" ],
         CC               => "clang",