make.bash: disable GOEXPERIMENT when using bootstrap toolchain

When using Go 1.4 this doesn't matter, but when using Go 1.17,
the bootstrap toolchain will complain about unknown GOEXPERIMENT settings.
Clearly GOEXPERIMENT is for the toolchain being built, not the bootstrap.

Already submitted as CL 395879 on the dev.boringcrypto branch,
but needed on master to set up GOEXPERIMENT=boringcrypto
builder ahead of merge.

For #51940.

Change-Id: Ib6a4099cca799b4d5df1974cdb5471adb0fd557d
Reviewed-on: https://go-review.googlesource.com/c/go/+/397894
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/make.bash

@@ -193,7 +193,7 @@ fi
 # Get the exact bootstrap toolchain version to help with debugging.
 # We clear GOOS and GOARCH to avoid an ominous but harmless warning if
 # the bootstrap doesn't support them.
-GOROOT_BOOTSTRAP_VERSION=$(GOOS= GOARCH= $GOROOT_BOOTSTRAP/bin/go version | sed 's/go version //')
+GOROOT_BOOTSTRAP_VERSION=$(GOOS= GOARCH= GOEXPERIMENT= $GOROOT_BOOTSTRAP/bin/go version | sed 's/go version //')
 echo "Building Go cmd/dist using $GOROOT_BOOTSTRAP. ($GOROOT_BOOTSTRAP_VERSION)"
 if $verbose; then
 	echo cmd/dist
@@ -204,7 +204,7 @@ if [ "$GOROOT_BOOTSTRAP" = "$GOROOT" ]; then
 	exit 1
 fi
 rm -f cmd/dist/dist
-GOROOT="$GOROOT_BOOTSTRAP" GOOS="" GOARCH="" GO111MODULE=off "$GOROOT_BOOTSTRAP/bin/go" build -o cmd/dist/dist ./cmd/dist
+GOROOT="$GOROOT_BOOTSTRAP" GOOS="" GOARCH="" GO111MODULE=off GOEXPERIMENT="" "$GOROOT_BOOTSTRAP/bin/go" build -o cmd/dist/dist ./cmd/dist
 
 # -e doesn't propagate out of eval, so check success by hand.
 eval $(./cmd/dist/dist env -p || echo FAIL=true)

src/make.bat

@@ -100,6 +100,7 @@ set GOROOT=%GOROOT_BOOTSTRAP%
 set GOOS=
 set GOARCH=
 set GOBIN=
+set GOEXPERIMENT=
 set GO111MODULE=off
 "%GOROOT_BOOTSTRAP%\bin\go.exe" build -o cmd\dist\dist.exe .\cmd\dist
 endlocal

src/make.rc

@@ -88,7 +88,7 @@ if(~ $GOROOT_BOOTSTRAP $GOROOT){
 echo 'Building Go cmd/dist using '^$GOROOT_BOOTSTRAP
 if(~ $#vflag 1)
 	echo cmd/dist
-GOROOT=$GOROOT_BOOTSTRAP GOOS='' GOARCH='' GO111MODULE=off $GOROOT_BOOTSTRAP/bin/go build -o cmd/dist/dist ./cmd/dist
+GOROOT=$GOROOT_BOOTSTRAP GOOS='' GOARCH='' GOEXPERIMENT='' GO111MODULE=off $GOROOT_BOOTSTRAP/bin/go build -o cmd/dist/dist ./cmd/dist
 
 eval `{./cmd/dist/dist env -9}
 if(~ $#vflag 1)