internal/buildcfg: enable regabi for Android

This will permit us to write ABIInternal assembler code for linux-amd64.

For #40724

Change-Id: I681866651554eda4229d6faa7f0c1ba42d07e57d
Reviewed-on: https://go-review.googlesource.com/c/go/+/315390
Trust: Ian Lance Taylor <[email protected]>
Run-TryBot: Ian Lance Taylor <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Cherry Zhang <[email protected]>

Author: ianlancetaylor

src/internal/buildcfg/exp.go

@@ -20,7 +20,7 @@ import (
 // was built with.)
 var Experiment goexperiment.Flags = parseExperiments()
 
-var regabiSupported = GOARCH == "amd64" && (GOOS == "linux" || GOOS == "darwin" || GOOS == "windows")
+var regabiSupported = GOARCH == "amd64" && (GOOS == "android" || GOOS == "linux" || GOOS == "darwin" || GOOS == "windows")
 
 // experimentBaseline specifies the experiment flags that are enabled by
 // default in the current toolchain. This is, in effect, the "control"