sv.h Convert _SV_HEAD_DEBUG to legal name

Author: khwilliamson

sv.h

@@ -228,18 +228,18 @@ typedef struct hek HEK;
         GP*	svu_gp;			\
         PerlIO *svu_fp;			\
     }	sv_u				\
-    _SV_HEAD_DEBUG
+    SV_HEAD_DEBUG_
 
 #ifdef DEBUG_LEAKING_SCALARS
-#define _SV_HEAD_DEBUG ;\
+#define SV_HEAD_DEBUG_ ;\
     PERL_BITFIELD32 sv_debug_optype:9;	/* the type of OP that allocated us */ \
     PERL_BITFIELD32 sv_debug_inpad:1;	/* was allocated in a pad for an OP */ \
     PERL_BITFIELD32 sv_debug_line:16;	/* the line where we were allocated */ \
     UV		    sv_debug_serial;	/* serial number of sv allocation   */ \
     char *	    sv_debug_file;	/* the file where we were allocated */ \
     SV *	    sv_debug_parent	/* what we were cloned from (ithreads)*/
 #else
-#define _SV_HEAD_DEBUG
+#define SV_HEAD_DEBUG_
 #endif
 
 struct STRUCT_SV {		/* struct sv { */