unix: remove _SC_PAGESIZE on Solaris

CL 62111 removed the _SC_PAGESIZE definition from the types_*.go files
but did not re-generate ztypes_solaris_amd64.go. Do so now to get rid of
_SC_PAGESIZE there as well.

Change-Id: Icde4366f4b7a92e8a89170ad00ff2b807e7655e1
Reviewed-on: https://go-review.googlesource.com/64350Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/ztypes_solaris_amd64.go

@@ -413,8 +413,6 @@ type BpfHdr struct {
 	Pad_cgo_0 [2]byte
 }
 
-const _SC_PAGESIZE = 0xb
-
 type Termios struct {
 	Iflag     uint32
 	Oflag     uint32