Rename PQsetSSLKeyPassHook and friends

4dc6355210 provided a way for libraries and clients to modify how libpq
handles client certificate passphrases, by installing a hook. However,
these routines are quite specific to how OpenSSL works, so it's
misleading and not future-proof to have these names not refer to OpenSSL.
Change all the names to add "_OpenSSL" after "Hook", and fix the docs
accordingly.

Author: Daniel Gustafsson

Discussion: https://postgr.es/m/981DE552-E399-45C2-9F60-3F0E3770CC61@yesql.se

src/interfaces/libpq/fe-secure.c

@@ -431,20 +431,20 @@ PQsslAttributeNames(PGconn *conn)
 	return result;
 }
 
-PQsslKeyPassHook_type
-PQgetSSLKeyPassHook(void)
+PQsslKeyPassHook_OpenSSL_type
+PQgetSSLKeyPassHook_OpenSSL(void)
 {
 	return NULL;
 }
 
 void
-PQsetSSLKeyPassHook(PQsslKeyPassHook_type hook)
+PQsetSSLKeyPassHook_OpenSSL(PQsslKeyPassHook_OpenSSL_type hook)
 {
 	return;
 }
 
 int
-PQdefaultSSLKeyPassHook(char *buf, int size, PGconn *conn)
+PQdefaultSSLKeyPassHook_OpenSSL(char *buf, int size, PGconn *conn)
 {
 	return 0;
 }