Move poll.h functions into their own directory.

libc/Makefile

@@ -288,9 +288,9 @@ netdb/setprotoent.o \
 netdb/setservent.o \
 pathconf.o \
 pipe.o \
-poll.o \
+poll/poll.o \
+poll/ppoll.o \
 popen.o \
-ppoll.o \
 preadv.o \
 print.o \
 psignal.o \

libc/poll/poll.cpp

@@ -17,7 +17,7 @@
     You should have received a copy of the GNU Lesser General Public License
     along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
 
-    poll.cpp
+    poll/poll.cpp
     Input/output multiplexing.
 
 *******************************************************************************/

libc/poll/ppoll.cpp

@@ -17,7 +17,7 @@
     You should have received a copy of the GNU Lesser General Public License
     along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
 
-    ppoll.cpp
+    poll/ppoll.cpp
     Input/output multiplexing.
 
 *******************************************************************************/