syscall: unexport GetCurrentProcessId on Windows

This slipped in with the implementation of Getpid in CL 5909043.
I'd exclude that CL entirely but it is tangled up in the Win32finddata changes.

R=golang-dev, minux.ma
CC=golang-dev
https://golang.org/cl/6297065

src/pkg/syscall/syscall_windows.go

@@ -201,7 +201,7 @@ func NewCallback(fn interface{}) uintptr
 //sys	RegQueryInfoKey(key Handle, class *uint16, classLen *uint32, reserved *uint32, subkeysLen *uint32, maxSubkeyLen *uint32, maxClassLen *uint32, valuesLen *uint32, maxValueNameLen *uint32, maxValueLen *uint32, saLen *uint32, lastWriteTime *Filetime) (regerrno error) = advapi32.RegQueryInfoKeyW
 //sys	RegEnumKeyEx(key Handle, index uint32, name *uint16, nameLen *uint32, reserved *uint32, class *uint16, classLen *uint32, lastWriteTime *Filetime) (regerrno error) = advapi32.RegEnumKeyExW
 //sys	RegQueryValueEx(key Handle, name *uint16, reserved *uint32, valtype *uint32, buf *byte, buflen *uint32) (regerrno error) = advapi32.RegQueryValueExW
-//sys	GetCurrentProcessId() (pid uint32) = kernel32.GetCurrentProcessId
+//sys	getCurrentProcessId() (pid uint32) = kernel32.GetCurrentProcessId
 
 // syscall interface implementation for other packages
 
@@ -702,7 +702,7 @@ func SetsockoptIPMreq(fd Handle, level, opt int, mreq *IPMreq) (err error) {
 }
 func SetsockoptIPv6Mreq(fd Handle, level, opt int, mreq *IPv6Mreq) (err error) { return EWINDOWS }
 
-func Getpid() (pid int) { return int(GetCurrentProcessId()) }
+func Getpid() (pid int) { return int(getCurrentProcessId()) }
 
 func FindFirstFile(name *uint16, data *Win32finddata) (handle Handle, err error) {
 	// NOTE(rsc): The Win32finddata struct is wrong for the system call:

src/pkg/syscall/zsyscall_windows_386.go

@@ -1181,7 +1181,7 @@ func RegQueryValueEx(key Handle, name *uint16, reserved *uint32, valtype *uint32
 	return
 }
 
-func GetCurrentProcessId() (pid uint32) {
+func getCurrentProcessId() (pid uint32) {
 	r0, _, _ := Syscall(procGetCurrentProcessId.Addr(), 0, 0, 0, 0)
 	pid = uint32(r0)
 	return

src/pkg/syscall/zsyscall_windows_amd64.go

@@ -1181,7 +1181,7 @@ func RegQueryValueEx(key Handle, name *uint16, reserved *uint32, valtype *uint32
 	return
 }
 
-func GetCurrentProcessId() (pid uint32) {
+func getCurrentProcessId() (pid uint32) {
 	r0, _, _ := Syscall(procGetCurrentProcessId.Addr(), 0, 0, 0, 0)
 	pid = uint32(r0)
 	return