syscall: regenerate Flock_t to make it compliant with EABI

Note that current z-files for linux/amd64,386,arm are based on 3.2 kernel.

LGTM=iant
R=golang-codereviews, dave, bradfitz, gobot, iant
CC=golang-codereviews
https://golang.org/cl/59160044

src/pkg/syscall/ztypes_linux_arm.go

@@ -147,9 +147,11 @@ type Fsid struct {
 type Flock_t struct {
 	Type      int16
 	Whence    int16
+	Pad_cgo_0 [4]byte
 	Start     int64
 	Len       int64
 	Pid       int32
+	Pad_cgo_1 [4]byte
 }
 
 type RawSockaddrInet4 struct {