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 <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Auto-Submit: Tobias Klauser <[email protected]>
Run-TryBot: Tobias Klauser <[email protected]>

Author: tklauser

unix/linux/Dockerfile

@@ -58,10 +58,9 @@ RUN apt-get update && apt-get install -y \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/*
 
-# Only for loong64, add patch and build golang
-RUN git clone https://go.googlesource.com/go --branch go1.18 /git/go \
-    && cd /git/loong64-patches && git checkout go-v1.18 && cd /git/go && git am /git/loong64-patches/*.patch \
-    && rm -rf /git/loong64-patches && cd /git/go/src && ./make.bash
+# Only for loong64, build Go from master until 1.19 is released
+RUN git clone https://go.googlesource.com/go --branch master /git/go \
+    && cd /git/go/src && ./make.bash
 
 ENV PATH /git/go/bin:$PATH