Removed termiosMask(..) and use the correct bitmask type

This requires a bit of copying in darwin 386/amd64 but simplifies
the overall design.

serial_darwin.go

@@ -11,48 +11,6 @@ import "syscall"
 const devFolder = "/dev"
 const regexFilter = "^(cu|tty)\\..*"
 
-// termios manipulation functions
-
-var baudrateMap = map[int]uint{
-	0:      syscall.B9600, // Default to 9600
-	50:     syscall.B50,
-	75:     syscall.B75,
-	110:    syscall.B110,
-	134:    syscall.B134,
-	150:    syscall.B150,
-	200:    syscall.B200,
-	300:    syscall.B300,
-	600:    syscall.B600,
-	1200:   syscall.B1200,
-	1800:   syscall.B1800,
-	2400:   syscall.B2400,
-	4800:   syscall.B4800,
-	9600:   syscall.B9600,
-	19200:  syscall.B19200,
-	38400:  syscall.B38400,
-	57600:  syscall.B57600,
-	115200: syscall.B115200,
-	230400: syscall.B230400,
-}
-
-var databitsMap = map[int]uint{
-	0: syscall.CS8, // Default to 8 bits
-	5: syscall.CS5,
-	6: syscall.CS6,
-	7: syscall.CS7,
-	8: syscall.CS8,
-}
-
-const tcCMSPAR uint = 0 // may be CMSPAR or PAREXT
-const tcIUCLC uint = 0
-
-const tcCCTS_OFLOW uint = 0x00010000
-const tcCRTS_IFLOW uint = 0x00020000
-
-const tcCRTSCTS uint = (tcCCTS_OFLOW | tcCRTS_IFLOW)
-
-// syscall wrappers
-
 //sys ioctl(fd int, req uint64, data uintptr) (err error)
 
 const ioctlTcgetattr = syscall.TIOCGETA