Set Windows timeouts to enforce non-blocking read

Settings ReadIntervalTimeout and ReadTotalTimeoutMultiplier to MAXDWORD
in the COMMTIMEOUTS structure on Windows makes Windows behave as
normally expected; a read call to the serial port will return
immediately if there is any data available, or if a single byte arrives
in the buffer. If no data arrives, it will timeout out after the timeout
specified in ReadTotalTimeoutConstant.

This fixes issues where reading from a serial port would take longer
than desired when less data arrives that there is room for in the buffer
passed to the read function.

See also: https://learn.microsoft.com/en-us/windows/win32/api/winbase/ns-winbase-commtimeouts

src/windows/com.rs

@@ -10,7 +10,7 @@ use winapi::um::handleapi::*;
 use winapi::um::processthreadsapi::GetCurrentProcess;
 use winapi::um::winbase::*;
 use winapi::um::winnt::{
-    DUPLICATE_SAME_ACCESS, FILE_ATTRIBUTE_NORMAL, GENERIC_READ, GENERIC_WRITE, HANDLE,
+    DUPLICATE_SAME_ACCESS, FILE_ATTRIBUTE_NORMAL, GENERIC_READ, GENERIC_WRITE, HANDLE, MAXDWORD,
 };
 
 use crate::windows::dcb;
@@ -243,8 +243,8 @@ impl SerialPort for COMPort {
         let milliseconds = timeout.as_millis();
 
         let mut timeouts = COMMTIMEOUTS {
-            ReadIntervalTimeout: 0,
-            ReadTotalTimeoutMultiplier: 0,
+            ReadIntervalTimeout: MAXDWORD,
+            ReadTotalTimeoutMultiplier: MAXDWORD,
             ReadTotalTimeoutConstant: milliseconds as DWORD,
             WriteTotalTimeoutMultiplier: 0,
             WriteTotalTimeoutConstant: milliseconds as DWORD,