Pass the right sizes to malloc() and realloc().

Reported by:	scan-build, via Mark Millard
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D16180

contrib/elftoolchain/elfcopy/sections.c

@@ -716,13 +716,13 @@ filter_reloc(struct elfcopy *ecp, struct section *s)
 #define	COPYREL(REL, SZ) do {					\
 	if (nrels == 0) {					\
 		if ((REL##SZ = malloc(cap *			\
-		    sizeof(Elf##SZ##_Rel))) == NULL)		\
+		    sizeof(*REL##SZ))) == NULL)			\
 			err(EXIT_FAILURE, "malloc failed");	\
 	}							\
 	if (nrels >= cap) {					\
 		cap *= 2;					\
 		if ((REL##SZ = realloc(REL##SZ, cap *		\
-		    sizeof(Elf##SZ##_Rel))) == NULL)		\
+		    sizeof(*REL##SZ))) == NULL)			\
 			err(EXIT_FAILURE, "realloc failed");	\
 	}							\
 	REL##SZ[nrels].r_offset = REL.r_offset;			\