Possibly incorrect masks for modem input status bits on Windows

[WarningImHack3r]

Since #187, the values of at least 4 pin status are computed with the wrong mask values:
https://github.com/bugst/go-serial/pull/187/files#diff-47ee85faa4e0440b94978b6193177ae093540d712fcea25742e36b3546357af8L244-L249

-const (
-	msCTSOn  = 0x0010
-	msDSROn  = 0x0020
-	msRingOn = 0x0040
-	msRLSDOn = 0x0080
-)

They have been replaced by variables from the go source of x/sys/windows, but these masks represent the value change event for the pin, not their actual values. The bug is at least here: https://github.com/bugst/go-serial/blob/master/serial_windows.go#L288-L293

Following the Microsoft docs, the correct masks to read the values are the following:

-CTS = 0x0008
+CTS = 0x0010
-DSR = 0x0010
+DSR = 0x0020
-RING = 0x0100
+RING = 0x0040
-RLSD = 0x0020
+RLSD = 0x0080

@twpayne implemented the events using these docs, which are not for the same purpose.

Values were in fact correct pre-1.6.3, and have been broken since this version.

[twpayne]

Thanks for spotting this and sorry for introducing the bug. Are you able to create a PR to fix this? Admittedly, I do not use this library on Windows.

Following the Microsoft docs, the correct masks to read the values are the following:

-CTS = 0x0008
+CTS = 0x0010
-DSR = 0x0010
+DSR = 0x0020
-RING = 0x0100
+RING = 0x0040
-RLSD = 0x0020
+RLSD = 0x0040

Should RLING and RLSD really have the same value (0x0040) here?

[WarningImHack3r]

Thanks for spotting this and sorry for introducing the bug. Are you able to create a PR to fix this? Admittedly, I do not use this library on Windows.

Fair enough! Yes I can make a PR, do you know if there are other places I need to change? I’ll search those constants across the repo

Should RLING and RLSD really have the same value (0x0040) here?

Oops! Good catch, edited the description; the goal is basically to revert to what it was originally, it matches the deleted snippet I quote at the beginning