Rename OPENSSL_CTX prefix to OSSL_LIB_CTX

Many of the new types introduced by OpenSSL 3.0 have an OSSL_ prefix,
e.g., OSSL_CALLBACK, OSSL_PARAM, OSSL_ALGORITHM, OSSL_SERIALIZER.

The OPENSSL_CTX type stands out a little by using a different prefix.
For consistency reasons, this type is renamed to OSSL_LIB_CTX.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/12621)
diff --git a/crypto/core_algorithm.c b/crypto/core_algorithm.c
index 68d6129..ddb9e5a 100644
--- a/crypto/core_algorithm.c
+++ b/crypto/core_algorithm.c
@@ -14,7 +14,7 @@
 #include "internal/provider.h"
 
 struct algorithm_data_st {
-    OPENSSL_CTX *libctx;
+    OSSL_LIB_CTX *libctx;
     int operation_id;            /* May be zero for finding them all */
     int (*pre)(OSSL_PROVIDER *, int operation_id, void *data, int *result);
     void (*fn)(OSSL_PROVIDER *, const OSSL_ALGORITHM *, int no_store,
@@ -85,7 +85,7 @@
     return ok;
 }
 
-void ossl_algorithm_do_all(OPENSSL_CTX *libctx, int operation_id,
+void ossl_algorithm_do_all(OSSL_LIB_CTX *libctx, int operation_id,
                            OSSL_PROVIDER *provider,
                            int (*pre)(OSSL_PROVIDER *, int operation_id,
                                       void *data, int *result),