cuse(3): annotate cuse_init() to suppress thread safety analysis
This avoids warnings from clang 21, similar to:
/usr/src/lib/libcuse/cuse_lib.c:111:14: error: writing variable 'h_cuse' requires holding mutex 'm_cuse' exclusively [-Werror,-Wthread-safety-analysis]
111 | TAILQ_INIT(&h_cuse);
| ^
/usr/src/lib/libcuse/cuse_lib.c:111:14: error: writing variable 'h_cuse' requires holding mutex 'm_cuse' exclusively [-Werror,-Wthread-safety-analysis]
/usr/src/lib/libcuse/cuse_lib.c:112:14: error: writing variable 'h_cuse_entered' requires holding mutex 'm_cuse' exclusively [-Werror,-Wthread-safety-analysis]
112 | TAILQ_INIT(&h_cuse_entered);
| ^
/usr/src/lib/libcuse/cuse_lib.c:112:14: error: writing variable 'h_cuse_entered' requires holding mutex 'm_cuse' exclusively [-Werror,-Wthread-safety-analysis]MFC after: 3 days
(cherry picked from commit 5629b5cf79934e0b94ddbbd93b7756f74fe4050a)