build: Define __USE_UNIX98 for old glibc

Otherwise PTHREAD_MUTEX_RECURSIVE isn't defined and we get an error
with old glibc.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/src/pcm/pcm_local.h b/src/pcm/pcm_local.h
index 32e6dcd..e4f6521 100644 (file)
--- a/src/pcm/pcm_local.h
+++ b/src/pcm/pcm_local.h
@@ -35,6 +35,7 @@
 #include "local.h"
 
 #ifdef THREAD_SAFE_API
+#define __USE_UNIX98 1 /* for old glibc */
 #include <pthread.h>
 #endif