diff -up thunderbird-147.0/comm/third_party/rust/glslopt/glsl-optimizer/include/c11/threads_posix.h.build-c11-threads-avail thunderbird-147.0/comm/third_party/rust/glslopt/glsl-optimizer/include/c11/threads_posix.h
--- thunderbird-147.0/comm/third_party/rust/glslopt/glsl-optimizer/include/c11/threads_posix.h.build-c11-threads-avail	2026-01-08 22:45:29.000000000 +0100
+++ thunderbird-147.0/comm/third_party/rust/glslopt/glsl-optimizer/include/c11/threads_posix.h	2026-01-14 15:46:09.864020742 +0100
@@ -66,7 +66,7 @@ typedef pthread_cond_t  cnd_t;
 typedef pthread_t       thrd_t;
 typedef pthread_key_t   tss_t;
 typedef pthread_mutex_t mtx_t;
-typedef pthread_once_t  once_flag;
+//typedef pthread_once_t  once_flag;
 
 
 /*
@@ -90,11 +90,13 @@ impl_thrd_routine(void *p)
 
 /*--------------- 7.25.2 Initialization functions ---------------*/
 // 7.25.2.1
+/*
 static inline void
 call_once(once_flag *flag, void (*func)(void))
 {
     pthread_once(flag, func);
 }
+*/
 
 
 /*------------- 7.25.3 Condition variable functions -------------*/
diff -up thunderbird-147.0/third_party/rust/glslopt/glsl-optimizer/include/c11/threads_posix.h.build-c11-threads-avail thunderbird-147.0/third_party/rust/glslopt/glsl-optimizer/include/c11/threads_posix.h
--- thunderbird-147.0/third_party/rust/glslopt/glsl-optimizer/include/c11/threads_posix.h.build-c11-threads-avail	2026-01-08 22:45:13.000000000 +0100
+++ thunderbird-147.0/third_party/rust/glslopt/glsl-optimizer/include/c11/threads_posix.h	2026-01-14 15:46:09.864193606 +0100
@@ -66,7 +66,7 @@ typedef pthread_cond_t  cnd_t;
 typedef pthread_t       thrd_t;
 typedef pthread_key_t   tss_t;
 typedef pthread_mutex_t mtx_t;
-typedef pthread_once_t  once_flag;
+//typedef pthread_once_t  once_flag;
 
 
 /*
@@ -90,12 +90,13 @@ impl_thrd_routine(void *p)
 
 /*--------------- 7.25.2 Initialization functions ---------------*/
 // 7.25.2.1
-static inline void
+//
+/*static inline void
 call_once(once_flag *flag, void (*func)(void))
 {
     pthread_once(flag, func);
 }
-
+*/
 
 /*------------- 7.25.3 Condition variable functions -------------*/
 // 7.25.3.1