Fix reference to symbol 'main'.

The AIX binder needs to be instructed that the output will have no entry
point (see AIX' ld manual: -e in the Flags section; autoexp and noentry
in the Binder section).

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8282)

Configurations/10-main.conf

@@ -1098,7 +1098,7 @@ my %targets = (
         dso_scheme       => "dlfcn",
         shared_target    => "aix",
         module_ldflags   => "-Wl,-G,-bsymbolic,-bexpall",
-        shared_ldflag    => "-Wl,-G,-bsymbolic",
+        shared_ldflag    => "-Wl,-G,-bsymbolic,-bnoentry",
         shared_defflag   => "-Wl,-bE:",
         perl_platform    => 'AIX',
     },