Note: this description is intentionally brief, as the full context for this issue is already presented in CDRIVER-4297.

In libmongocrypt, the following OpenSSL 1.1 functions are declared when compiling against OpenSSL 1.0.x:

• EVP_CIPHER_CTX_new and EVP_CIPHER_CTX_free, which are defined in src/crypto/libcrypto.c

These functions should either be declared statically or renamed/prefixed, as is done for some libbson compat functions.

Note: EVP_MD_CTX_new and EVP_MD_CTX_free are defined kms-message/src/kms_crypto_libcrypto.c, but those declarations already use static.