StdLib|LibC: Implement the sleep() function.

Implement the sleep() function and make both sleep() and usleep() public.  Required initially for Python, but these functions have general applicability.

Signed-off-by: duanev@gmail.com
Reviewed-by:   darylm503


git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12323 6f19259b-4bc3-4df7-8a09-765794883524

StdLib/LibC/Uefi/select.c

@@ -74,19 +74,14 @@
 
 #define MAX_SLEEP_DELAY 0xfffffffe
 
-//
-//  Name:
-//      usleep
-//
-//  Description:
-//      Implement usleep(3) function.
-//
-//  Arguments:
-//      Microseconds to sleep.
-//
-//  Returns:
-//      0
-//
+/** Sleep for the specified number of Microseconds.
+
+    Implements the usleep(3) function.
+
+    @param[in]    Microseconds    Number of microseconds to sleep.
+
+    @retval   0   Always returns zero.
+**/
 int
 usleep( useconds_t Microseconds )
 {
@@ -98,6 +93,12 @@ usleep( useconds_t Microseconds )
   return (0);
 }
 
+unsigned int
+sleep( unsigned int Seconds )
+{
+  return (usleep( useconds_t(Seconds * 1000000) ));
+}
+
 static int
 selscan(
   fd_mask **ibits,