Remove xcalloc() and convert its callers to xzalloc(). About half of them

were using "1" as one of the arguments anyway, and as for the rest a multiply
and a push isn't noticeably bigger than pushing two arguments on the stack.

findutils/grep.c

@@ -321,7 +321,7 @@ int grep_main(int argc, char **argv)
 		lines_before = 0;
 		lines_after = 0;
 	} else if(lines_before > 0)
-		before_buf = (char **)xcalloc(lines_before, sizeof(char *));
+		before_buf = (char **)xzalloc(lines_before * sizeof(char *));
   }
 #else
 	/* with auto sanity checks */

findutils/xargs.c

@@ -503,7 +503,7 @@ int xargs_main(int argc, char **argv)
 
 		/* allocating pointers for execvp:
 		   a*arg, n*arg from stdin, NULL */
-		args = xcalloc(n + a + 1, sizeof(char *));
+		args = xzalloc((n + a + 1) * sizeof(char *));
 
 		/* Store the command to be executed
 		   (taken from the command line) */