Log to stderr instead of stdout

"Non-output" logging should go to stderr in general.  Plugins printing to
stdout breaks breaks UNIX-style utilities that use it for formatted output.

Author: drobilla

src/dsp/src/gkick_log.c

@@ -28,7 +28,7 @@ gkick_log_msg(const char *message, ...)
 {
         va_list args;
         va_start (args, message);
-        vprintf (message, args);
+        vfprintf (stderr, message, args);
         va_end (args);
         printf("\n");
 }
@@ -39,7 +39,7 @@ gkick_msg_info(const char *msg, ...)
         va_list args;
         printf("Info: ");
         va_start (args, msg);
-        vprintf (msg, args);
+        vfprintf (stderr, msg, args);
         va_end (args);
         printf("\n");
 }
@@ -51,7 +51,7 @@ gkick_msg_error(const char *msg, ...)
         va_list args;
         printf("Error: ");
         va_start (args, msg);
-        vprintf (msg, args);
+        vfprintf (stderr, msg, args);
         va_end (args);
         printf("\n");
 }