Declare DllMain internally
Declare DllMain internally

DllMain is a symbol that needs to be global, but no one needs to know.
However, some compilers will warn if there isn't a declaration before
the function is defined.  Just add a declaration before the function
definition.

Reviewed-by: Kurt Roeckx <bb87b47479d83cec3c76132206933257ded727b2@openssl.org>

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl