Process: Allow timeout to be changed after child starts

Recompute `TimeoutTime` after `Timeout` changes so that one may modify
the timeout of a process after it has started running by calling the
normal `kwsysProcess_SetTimeout` method.

Change-Id: I460a02d0d3c5f107b844abb56e39f5c844e7e3fb

ProcessUNIX.c

@@ -505,6 +505,8 @@ void kwsysProcess_SetTimeout(kwsysProcess* cp, double timeout)
     {
     cp->Timeout = 0;
     }
+  // Force recomputation of TimeoutTime.
+  cp->TimeoutTime.tv_sec = -1;
 }
 
 /*--------------------------------------------------------------------------*/

ProcessWin32.c

@@ -698,6 +698,8 @@ void kwsysProcess_SetTimeout(kwsysProcess* cp, double timeout)
     {
     cp->Timeout = 0;
     }
+  // Force recomputation of TimeoutTime.
+  cp->TimeoutTime.QuadPart = -1;
 }
 
 /*--------------------------------------------------------------------------*/