lavu/thread: add an internal function for setting thread name

Linux-only for now.

configure

@@ -2310,6 +2310,7 @@ SYSTEM_FUNCS="
     nanosleep
     PeekNamedPipe
     posix_memalign
+    prctl
     pthread_cancel
     sched_getaffinity
     SecItemImport
@@ -6294,6 +6295,7 @@ check_func  mmap
 check_func  mprotect
 # Solaris has nanosleep in -lrt, OpenSolaris no longer needs that
 check_func_headers time.h nanosleep || check_lib nanosleep time.h nanosleep -lrt
+check_func_headers sys/prctl.h prctl
 check_func  sched_getaffinity
 check_func  setrlimit
 check_struct "sys/stat.h" "struct stat" st_mtim.tv_nsec -D_BSD_SOURCE

libavutil/thread.h

@@ -24,6 +24,12 @@
 
 #include "config.h"
 
+#if HAVE_PRCTL
+#include <sys/prctl.h>
+#endif
+
+#include "error.h"
+
 #if HAVE_PTHREADS || HAVE_W32THREADS || HAVE_OS2THREADS
 
 #if HAVE_PTHREADS
@@ -33,7 +39,6 @@
 
 #include <stdlib.h>
 
-#include "error.h"
 #include "log.h"
 #include "macros.h"
 
@@ -187,4 +192,13 @@ static inline int ff_thread_once(char *control, void (*routine)(void))
 
 #endif
 
+static inline int ff_thread_setname(const char *name)
+{
+#if HAVE_PRCTL
+    return AVERROR(prctl(PR_SET_NAME, name));
+#endif
+
+    return AVERROR(ENOSYS);
+}
+
 #endif /* AVUTIL_THREAD_H */