cmd/go: default to "exe" build mode for windows -race

This patch changes the default build mode from "pie" to "exe" when
building programs on windows with "-race" in effect. The Go command
already issues an error if users explicitly ask for -buildmode=pie in
combination with -race on windows, but wasn't revising the default
"pie" build mode if a specific buildmode was not requested.

Updates #53539.
Updates #35006.

Change-Id: I2f81a41a1d15a0b4f5ae943146175c5a1202cbe0
Reviewed-on: https://go-review.googlesource.com/c/go/+/416174
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Than McIntosh <thanm@google.com>

src/cmd/go/internal/work/init.go

@@ -211,7 +211,11 @@ func buildModeInit() {
 			codegenArg = "-shared"
 			ldBuildmode = "pie"
 		case "windows":
-			ldBuildmode = "pie"
+			if cfg.BuildRace {
+				ldBuildmode = "exe"
+			} else {
+				ldBuildmode = "pie"
+			}
 		case "ios":
 			codegenArg = "-shared"
 			ldBuildmode = "pie"