scheduler: Fix build failure on Linux with '-Werror -Wall'

The string which we add into array stays `const` after fixing OpenPrinting#814
(because `strdup()`, which caused memory leak returned `char *`)
and compiler fails because of it if it runs with '-Werror -Wall'.

scheduler/colorman.c

@@ -901,7 +901,7 @@ colord_create_device(
   DBusMessageIter dict;			/* D-Bus method arguments */
   DBusError	error;			/* D-Bus error */
   const char	*device_path;		/* Device object path */
-  char		*profile_path;		/* Profile path */
+  const char	*profile_path;		/* Profile path */
   char		device_id[1024];	/* Device ID as understood by colord */
   char		format_str[1024];	/* Qualifier format as a string */
 
@@ -1014,7 +1014,7 @@ colord_create_profile(
   DBusError	error;			/* D-Bus error */
   char		*idstr;			/* Profile ID string */
   size_t	idstrlen;		/* Profile ID allocated length */
-  const char	*profile_path;		/* Device object path */
+  char		*profile_path;		/* Device object path */
   char		format_str[1024];	/* Qualifier format as a string */