Get rid of outdated sched_yield.h temporary wrapper

The main utility of "sched_yield.h" was to provide sched_yield() on
OS'ed which didn't have it back in 2007, such as OpenBSD and NetBSD.

Nowadays, the landscape is different, with the issue having been fixed
in both above OS'es.  Moreover, by getting rid of the wrapper, we avoid
"missing -DHAVE_SCHED_YIELD" problems on architectures such as ARM (see
commit f8ad265, where the issue was caused by this wrapper header
exclusively).

Makefile.defs

@@ -1416,7 +1416,7 @@ LIBS+= -ldl -lresolv
 
 #os specific stuff
 ifeq ($(OS), linux)
-	DEFS+=-DHAVE_GETHOSTBYNAME2 -DHAVE_UNION_SEMUN -DHAVE_SCHED_YIELD \
+	DEFS+=-DHAVE_GETHOSTBYNAME2 -DHAVE_UNION_SEMUN \
 			-DHAVE_MSG_NOSIGNAL -DHAVE_MSGHDR_MSG_CONTROL -DHAVE_ALLOCA_H \
 			-DHAVE_TIMEGM
 	ifneq ($(found_lock_method), yes)
@@ -1449,7 +1449,7 @@ ifeq ($(OS), linux)
 endif
 
 ifeq ($(OS), gnu_kfreebsd)
-	DEFS+=-DHAVE_GETHOSTBYNAME2 -DHAVE_UNION_SEMUN -DHAVE_SCHED_YIELD \
+	DEFS+=-DHAVE_GETHOSTBYNAME2 -DHAVE_UNION_SEMUN \
 			-DHAVE_MSG_NOSIGNAL -DHAVE_MSGHDR_MSG_CONTROL -DHAVE_ALLOCA_H \
 			-DHAVE_TIMEGM
 	ifneq ($(found_lock_method), yes)
@@ -1468,7 +1468,7 @@ ifeq ($(OS), gnu_kfreebsd)
 endif
 
 ifeq  ($(OS), solaris)
-	DEFS+= -DHAVE_GETIPNODEBYNAME -DHAVE_SYS_SOCKIO_H -DHAVE_SCHED_YIELD \
+	DEFS+= -DHAVE_GETIPNODEBYNAME -DHAVE_SYS_SOCKIO_H \
 			-DHAVE_ALLOCA_H -DUSE_SIGACTION -D_POSIX_PTHREAD_SEMANTICS
 	ifneq ($(found_lock_method), yes)
 		DEFS+= -DUSE_PTHREAD_MUTEX  # try pthread sems
@@ -1509,9 +1509,8 @@ endif
 
 ifeq ($(OS), freebsd)
 	DEFS+=-DHAVE_SOCKADDR_SA_LEN -DHAVE_GETHOSTBYNAME2 -DHAVE_UNION_SEMUN \
-		-DHAVE_SCHED_YIELD -DHAVE_MSGHDR_MSG_CONTROL \
-		-DHAVE_CONNECT_ECONNRESET_BUG -DHAVE_TIMEGM \
-		-DHAVE_NETINET_IN_SYSTM
+		-DHAVE_MSGHDR_MSG_CONTROL -DHAVE_CONNECT_ECONNRESET_BUG \
+		-DHAVE_TIMEGM -DHAVE_NETINET_IN_SYSTM
 	LIBS=  $(_SAVE_LIBS) #resolver & dlopen is in libc
 	ifneq ($(found_lock_method), yes)
 		DEFS+= -DUSE_PTHREAD_MUTEX  # try pthread sems
@@ -1596,8 +1595,7 @@ endif
 # OS X support, same as freebsd
 ifeq ($(OS), darwin)
 	DEFS+=-DHAVE_SOCKADDR_SA_LEN -DHAVE_GETHOSTBYNAME2 -DHAVE_UNION_SEMUN \
-		-DHAVE_SCHED_YIELD -DHAVE_MSGHDR_MSG_CONTROL \
-		-DUSE_ANON_MMAP \
+		-DHAVE_MSGHDR_MSG_CONTROL -DUSE_ANON_MMAP \
 		-DNDEBUG -DHAVE_CONNECT_ECONNRESET_BUG -DHAVE_TIMEGM
 	# -DNDEBUG used to turn off assert (assert wants to call
 	# eprintf which doesn't seem to be defined in any shared lib

fastlock.h

@@ -48,7 +48,7 @@
 #ifndef fastlock_h
 #define fastlock_h
 
-#include "sched_yield.h"
+#include <sched.h>
 
 
 #define SPIN_OPTIMIZE /* if defined optimize spining on the lock:

modules/event_stream/event_stream.h

@@ -32,12 +32,4 @@
 #define COLON_C			':'
 #define SLASH_C			'/'
 
-#ifdef HAVE_SCHED_YIELD
-#include <sched.h>
-#else
-#include <unistd.h>
-/** Fake sched_yield if no unistd.h include is available */
-        #define sched_yield()   sleep(0)
-#endif /* HAVE_SCHED_YIELD */
-
 #endif

modules/event_xmlrpc/event_xmlrpc.h

@@ -42,11 +42,3 @@ struct xmlrpc_sock_param {
 };
 
 #endif
-
-#ifdef HAVE_SCHED_YIELD
-#include <sched.h>
-#else
-#include <unistd.h>
-/** Fake sched_yield if no unistd.h include is available */
-        #define sched_yield()   sleep(0)
-#endif

pt.c

@@ -22,7 +22,6 @@
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <unistd.h>
-#include <sched.h>
 #include <stdio.h>
 
 #include "lib/dbg/profiling.h"