Remove mallocarray(...) and use reallocarray(NULL, ...)

After a short correspondence with Otto Moerbeek it turned out
mallocarray() is only in the OpenBSD-Kernel, because the kernel-
malloc doesn't have realloc.
Userspace applications should rather use reallocarray with an
explicit NULL-pointer.

Assuming reallocarray() will become available in c-stdlibs in the
next few years, we nip mallocarray() in the bud to allow an easy
transition to a system-provided version when the day comes.

paste.c

@@ -107,11 +107,11 @@ main(int argc, char *argv[])
 
 	/* populate delimiters */
 	unescape(adelim);
-	delim = emallocarray(utflen(adelim) + 1, sizeof(*delim));
+	delim = ereallocarray(NULL, utflen(adelim) + 1, sizeof(*delim));
 	len = utftorunestr(adelim, delim);
 
 	/* populate file list */
-	dsc = emallocarray(argc, sizeof(*dsc));
+	dsc = ereallocarray(NULL, argc, sizeof(*dsc));
 
 	for (i = 0; i < argc; i++) {
 		if (strcmp(argv[i], "-") == 0)