CI/GCC: Add Fedora 44, fix build errors and threadsappend

- Add Fedora 44 to CI tests
- Fix build issues from the newer compiler. These are mostly 'char *'
  to 'const char *' conversions.
- Fix threadsappend.c test waiting for the same thread TID twice.
  This caused the test to hang on F44 (but strangely not other OSs?)

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <alexander.motin@TrueNAS.com>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #18478

module/zfs/dmu_objset.c

@@ -3011,7 +3011,7 @@ dmu_objset_get_user(objset_t *os)
 int
 dmu_fsname(const char *snapname, char *buf)
 {
-	char *atp = strchr(snapname, '@');
+	const char *atp = strchr(snapname, '@');
 	if (atp == NULL)
 		return (SET_ERROR(EINVAL));
 	if (atp - snapname >= ZFS_MAX_DATASET_NAME_LEN)

module/zfs/dsl_bookmark.c

@@ -39,10 +39,10 @@
 
 static int
 dsl_bookmark_hold_ds(dsl_pool_t *dp, const char *fullname,
-    dsl_dataset_t **dsp, const void *tag, char **shortnamep)
+    dsl_dataset_t **dsp, const void *tag, const char **shortnamep)
 {
 	char buf[ZFS_MAX_DATASET_NAME_LEN];
-	char *hashp;
+	const char *hashp;
 
 	if (strlen(fullname) >= ZFS_MAX_DATASET_NAME_LEN)
 		return (SET_ERROR(ENAMETOOLONG));
@@ -105,7 +105,7 @@ int
 dsl_bookmark_lookup(dsl_pool_t *dp, const char *fullname,
     dsl_dataset_t *later_ds, zfs_bookmark_phys_t *bmp)
 {
-	char *shortname;
+	const char *shortname;
 	dsl_dataset_t *ds;
 	int error;
 
@@ -219,7 +219,7 @@ dsl_bookmark_create_check_impl(dsl_pool_t *dp,
 
 	int error;
 	dsl_dataset_t *newbm_ds;
-	char *newbm_short;
+	const char *newbm_short;
 	zfs_bookmark_phys_t bmark_phys;
 
 	error = dsl_bookmark_hold_ds(dp, newbm, &newbm_ds, FTAG, &newbm_short);
@@ -329,7 +329,7 @@ dsl_bookmark_create_check(void *arg, dmu_tx_t *tx)
 }
 
 static dsl_bookmark_node_t *
-dsl_bookmark_node_alloc(char *shortname)
+dsl_bookmark_node_alloc(const char *shortname)
 {
 	dsl_bookmark_node_t *dbn = kmem_alloc(sizeof (*dbn), KM_SLEEP);
 	dbn->dbn_name = spa_strdup(shortname);
@@ -445,7 +445,7 @@ dsl_bookmark_create_sync_impl_snap(const char *bookmark, const char *snapshot,
 	dsl_pool_t *dp = dmu_tx_pool(tx);
 	objset_t *mos = dp->dp_meta_objset;
 	dsl_dataset_t *snapds, *bmark_fs;
-	char *shortname;
+	const char *shortname;
 	boolean_t bookmark_redacted;
 	uint64_t *dsredactsnaps;
 	uint64_t dsnumsnaps;
@@ -535,7 +535,7 @@ dsl_bookmark_create_sync_impl_book(
 {
 	dsl_pool_t *dp = dmu_tx_pool(tx);
 	dsl_dataset_t *bmark_fs_source, *bmark_fs_new;
-	char *source_shortname, *new_shortname;
+	const char *source_shortname, *new_shortname;
 	zfs_bookmark_phys_t source_phys;
 
 	VERIFY0(dsl_bookmark_hold_ds(dp, source_name, &bmark_fs_source, FTAG,
@@ -1106,7 +1106,7 @@ dsl_bookmark_destroy_check(void *arg, dmu_tx_t *tx)
 		dsl_dataset_t *ds;
 		zfs_bookmark_phys_t bm;
 		int error;
-		char *shortname;
+		const char *shortname;
 
 		error = dsl_bookmark_hold_ds(dp, fullname, &ds,
 		    FTAG, &shortname);
@@ -1162,7 +1162,7 @@ dsl_bookmark_destroy_sync(void *arg, dmu_tx_t *tx)
 	for (nvpair_t *pair = nvlist_next_nvpair(dbda->dbda_success, NULL);
 	    pair != NULL; pair = nvlist_next_nvpair(dbda->dbda_success, pair)) {
 		dsl_dataset_t *ds;
-		char *shortname;
+		const char *shortname;
 		uint64_t zap_cnt;
 
 		VERIFY0(dsl_bookmark_hold_ds(dp, nvpair_name(pair),

module/zfs/dsl_dir.c

@@ -417,7 +417,7 @@ dsl_dir_namelen(dsl_dir_t *dd)
 static int
 getcomponent(const char *path, char *component, const char **nextp)
 {
-	char *p;
+	const char *p;
 
 	if ((path == NULL) || (path[0] == '\0'))
 		return (SET_ERROR(ENOENT));