A bit more format warning squelching.

Inspired by patch from Timo Sirainen.  Most of them are not
strictly necessary but making warnings less chatty would help
spot real bugs later.

Signed-off-by: Junio C Hamano <junkio@cox.net>

convert-cache.c

@@ -60,7 +60,7 @@ static void convert_ascii_sha1(void *buffer)
 	struct entry *entry;
 
 	if (get_sha1_hex(buffer, sha1))
-		die("expected sha1, got '%s'", buffer);
+		die("expected sha1, got '%s'", (char*) buffer);
 	entry = convert_entry(sha1);
 	memcpy(buffer, sha1_to_hex(entry->new_sha1), 40);
 }
@@ -272,7 +272,7 @@ static void convert_commit(void *buffer, unsigned long size, unsigned char *resu
 	unsigned long orig_size = size;
 
 	if (memcmp(buffer, "tree ", 5))
-		die("Bad commit '%s'", buffer);
+		die("Bad commit '%s'", (char*) buffer);
 	convert_ascii_sha1(buffer+5);
 	buffer += 46;    /* "tree " + "hex sha1" + "\n" */
 	while (!memcmp(buffer, "parent ", 7)) {

diff.c

@@ -134,8 +134,8 @@ static void builtin_diff(const char *name_a,
 			 int complete_rewrite)
 {
 	int i, next_at, cmd_size;
-	const char *diff_cmd = "diff -L%s%s -L%s%s";
-	const char *diff_arg  = "%s %s||:"; /* "||:" is to return 0 */
+	const char *const diff_cmd = "diff -L%s%s -L%s%s";
+	const char *const diff_arg  = "%s %s||:"; /* "||:" is to return 0 */
 	const char *input_name_sq[2];
 	const char *path0[2];
 	const char *path1[2];
@@ -782,7 +782,8 @@ static void diff_flush_raw(struct diff_filepair *p,
 	char status[10];
 
 	if (line_termination) {
-		const char *err = "path %s cannot be expressed without -z";
+		const char *const err =
+			"path %s cannot be expressed without -z";
 		if (strchr(p->one->path, line_termination) ||
 		    strchr(p->one->path, inter_name_termination))
 			die(err, p->one->path);