unix/linux: use gotip instead of patched Go 1.18

CL 399336 added support for generating linux/loong64 types and constants
by using a patched version of Go 1.18. The necessary changes have since
been submitted to gotip, so use Go build from the master branch to
generate types and consts.

The changes in the cgo -godefs generated comments are due to CL 396936,
also see go.dev/issue/52063

Change-Id: I314156675e79ba77b9eb1fa1845b20ca974ec77a
Reviewed-on: https://go-review.googlesource.com/c/sys/+/406794
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
diff --git a/unix/zerrors_linux_mips64le.go b/unix/zerrors_linux_mips64le.go
index 496364c..f5367a9 100644
--- a/unix/zerrors_linux_mips64le.go
+++ b/unix/zerrors_linux_mips64le.go
@@ -5,7 +5,7 @@
 // +build mips64le,linux
 
 // Code generated by cmd/cgo -godefs; DO NOT EDIT.
-// cgo -godefs -- -Wall -Werror -static -I/tmp/include /build/unix/_const.go
+// cgo -godefs -- -Wall -Werror -static -I/tmp/include _const.go
 
 package unix