patch: make CRYPTO_get_ex_new_index not return 0

[Marc Aldorasi]

The man page for CRYPTO_get_ex_new_index says that "the value 0 is
reserved for the legacy "app_data" APIs", but the function can still
return 0, which can cause issues for programs that use both APIs.  The
attached patch causes the returned indices to start at 1 instead.

See also the corresponding OpenSSL bug report:
https://marc.info/?l=openssl-dev&m=142421750627504&w=2

diff --git a/src/lib/libcrypto/ex_data.c b/src/lib/libcrypto/ex_data.c
index b1e391366..d9c39b2c4 100644
--- a/src/lib/libcrypto/ex_data.c
+++ b/src/lib/libcrypto/ex_data.c
@@ -320,7 +320,7 @@ def_get_class(int class_index)
                gen = malloc(sizeof(EX_CLASS_ITEM));
                if (gen) {
                        gen->class_index = class_index;
-                       gen->meth_num = 0;
+                       gen->meth_num = 1;
                        gen->meth = sk_CRYPTO_EX_DATA_FUNCS_new_null();
                        if (!gen->meth)
                                free(gen);