streams: remove unused tls functions

The implementations of git_openssl_stream_new and
git_mbedtls_stream_new have callers protected by #ifdefs and
are never called unless compiled in.  There's no need for a
dummy implementation.  Remove them.

src/streams/mbedtls.c

@@ -490,23 +490,4 @@ int git_mbedtls_stream_global_init(void)
 	return 0;
 }
 
-int git_mbedtls_stream_new(git_stream **out, const char *host, const char *port)
-{
-	GIT_UNUSED(out);
-	GIT_UNUSED(host);
-	GIT_UNUSED(port);
-
-	giterr_set(GITERR_SSL, "mbedTLS is not supported in this version");
-	return -1;
-}
-
-int git_mbedtls__set_cert_location(const char *path, int is_dir)
-{
-	GIT_UNUSED(path);
-	GIT_UNUSED(is_dir);
-
-	giterr_set(GITERR_SSL, "mbedTLS is not supported in this version");
-	return -1;
-}
-
 #endif

src/streams/mbedtls.h

@@ -13,9 +13,11 @@
 
 extern int git_mbedtls_stream_global_init(void);
 
+#ifdef GIT_MBEDTLS
+extern int git_mbedtls__set_cert_location(const char *path, int is_dir);
+
 extern int git_mbedtls_stream_new(git_stream **out, const char *host, const char *port);
 extern int git_mbedtls_stream_wrap(git_stream **out, git_stream *in, const char *host);
-
-extern int git_mbedtls__set_cert_location(const char *path, int is_dir);
+#endif
 
 #endif

src/streams/openssl.c

@@ -799,23 +799,4 @@ int git_openssl_set_locking(void)
 	return -1;
 }
 
-int git_openssl_stream_new(git_stream **out, const char *host, const char *port)
-{
-	GIT_UNUSED(out);
-	GIT_UNUSED(host);
-	GIT_UNUSED(port);
-
-	giterr_set(GITERR_SSL, "openssl is not supported in this version");
-	return -1;
-}
-
-int git_openssl__set_cert_location(const char *file, const char *path)
-{
-	GIT_UNUSED(file);
-	GIT_UNUSED(path);
-
-	giterr_set(GITERR_SSL, "openssl is not supported in this version");
-	return -1;
-}
-
 #endif

src/streams/openssl.h

@@ -13,9 +13,11 @@
 
 extern int git_openssl_stream_global_init(void);
 
+#ifdef GIT_OPENSSL
+extern int git_openssl__set_cert_location(const char *file, const char *path);
+
 extern int git_openssl_stream_new(git_stream **out, const char *host, const char *port);
 extern int git_openssl_stream_wrap(git_stream **out, git_stream *in, const char *host);
-
-extern int git_openssl__set_cert_location(const char *file, const char *path);
+#endif
 
 #endif

src/streams/stransport.h

@@ -11,7 +11,11 @@
 
 #include "git2/sys/stream.h"
 
+#ifdef GIT_SECURE_TRANSPORT
+
 extern int git_stransport_stream_new(git_stream **out, const char *host, const char *port);
 extern int git_stransport_stream_wrap(git_stream **out, git_stream *in, const char *host);
 
 #endif
+
+#endif