Remove const char * const return value

A function can't return something of that type, but this has always been
a macro, so this hasn't been caught.

Author: khwilliamson

embed.fnc

@@ -2689,8 +2689,7 @@ CTp	|Signal_t|perly_sighandler					\
 				|NULLOK void *uap			\
 				|bool safe
 
-Admp	|const char * const|phase_name					\
-				|enum perl_phase phase
+Admp	|const char *|phase_name|enum perl_phase phase
 Adp	|void	|pmop_dump	|NULLOK PMOP *pm
 : Used in perly.y
 p	|OP *	|pmruntime	|NN OP *o				\