Committed: io/async.h: Use __gthread_mutex_t, not pthread_mutex_t.

[Hans-Peter Nilsson <hans-peter.nilsson@axis.com>]

These pthread_mutex_t were obviously meant to be
__gthread_mutex_t.  See other declarations.  Not being that,
broke cris-elf build at r264070, restored with this patch.  Also
regtested on native x86_64-pc-linux-gnu.

I'm not sure know why no other bare-iron target saw this, but
perhaps it's because my newlib is a bit dated (...looks... yes,
looks like newlib has grown pthreads since then, but that
doesn't excuse this flaw).  Still, there may be other similar
flaws behind #ifdefs, this is just a build-fixing patch.

Committed as obvious.

libgfortran:
	* io/async.h: Use __gthread_mutex_t, not pthread_mutex_t.

Index: libgfortran/io/async.h
===================================================================
--- libgfortran/io/async.h	(revision 264070)
+++ libgfortran/io/async.h	(working copy)
@@ -337,8 +337,8 @@ struct adv_cond
 
 typedef struct async_unit
 {
-  pthread_mutex_t io_lock;   /* Lock for doing actual I/O. */
-  pthread_mutex_t lock;      /* Lock for manipulating the queue structure.  */
+  __gthread_mutex_t io_lock;   /* Lock for doing actual I/O. */
+  __gthread_mutex_t lock;      /* Lock for manipulating the queue structure.  */
   bool empty;
   struct
   {

brgds, H-P