ossl.h: include <openssl/provider.h> in ossl.h

Move the #include from ossl_provider.c to ossl.h. As OpenSSL 3 provider
functions will be used in multiple source files, having it in the
common header file is convenient.

Author: rhenium

ext/openssl/ossl.h

@@ -71,6 +71,7 @@
 
 #if OSSL_OPENSSL_PREREQ(3, 0, 0)
 # define OSSL_USE_PROVIDER
+# include <openssl/provider.h>
 #endif
 
 /*

ext/openssl/ossl_provider.c

@@ -5,8 +5,6 @@
 #include "ossl.h"
 
 #ifdef OSSL_USE_PROVIDER
-# include <openssl/provider.h>
-
 #define NewProvider(klass) \
     TypedData_Wrap_Struct((klass), &ossl_provider_type, 0)
 #define SetProvider(obj, provider) do { \