Cleaned up patch based on
https://github.com/xarblu/sysbits/blob/72296ccadaca4c245e713fcf5375a7449c2855d0/etc/portage/patches/mail-client/thunderbird/00-glibc-2.43.patch

--- a/third_party/rust/glslopt/glsl-optimizer/include/c11/threads_posix.h.orig
+++ b/third_party/rust/glslopt/glsl-optimizer/include/c11/threads_posix.h
@@ -51,7 +51,6 @@ Configuration macro:
 #include <pthread.h>
 
 /*---------------------------- macros ----------------------------*/
-#define ONCE_FLAG_INIT PTHREAD_ONCE_INIT
 #ifdef INIT_ONCE_STATIC_INIT
 #define TSS_DTOR_ITERATIONS PTHREAD_DESTRUCTOR_ITERATIONS
 #else
@@ -66,7 +65,6 @@ 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;
 
 
 /*
@@ -88,15 +86,6 @@ 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 -------------*/
 // 7.25.3.1
 static inline int
--- a/security/sandbox/chromium/sandbox/linux/system_headers/linux_seccomp.h.orig
+++ b/security/sandbox/chromium/sandbox/linux/system_headers/linux_seccomp.h
@@ -214,8 +214,4 @@ struct seccomp_notif_addfd {
 #define SECCOMP_RET_INVALID 0x00010000U  // Illegal return value
 #endif
 
-#ifndef SYS_SECCOMP
-#define SYS_SECCOMP                   1
-#endif
-
 #endif  // SANDBOX_LINUX_SYSTEM_HEADERS_LINUX_SECCOMP_H_