Stop using DIST_DIR in Soong

We're only using it to distribute files in case of failure, which isn't
well supported currently, but can be handled for now by using the
DIST_DIR environment variable during the command execution.

This was at least one cause that we'd be re-running Soong during every
build server build, as the DIST_DIR values are unique.

Test: m dist
Change-Id: Ibd5e6b6c46695350de80b745bfb6a6aa685033a0

android/paths.go

@@ -725,46 +725,6 @@ func PathForIntermediates(ctx PathContext, paths ...string) OutputPath {
 	return PathForOutput(ctx, ".intermediates", path)
 }
 
-// DistPath is a Path representing a file path rooted from the dist directory
-type DistPath struct {
-	basePath
-}
-
-func (p DistPath) withRel(rel string) DistPath {
-	p.basePath = p.basePath.withRel(rel)
-	return p
-}
-
-var _ Path = DistPath{}
-
-// PathForDist joins the provided paths and returns a DistPath that is
-// validated to not escape the dist dir.
-// On error, it will return a usable, but invalid DistPath, and report a ModuleError.
-func PathForDist(ctx PathContext, pathComponents ...string) DistPath {
-	path, err := validatePath(pathComponents...)
-	if err != nil {
-		reportPathError(ctx, err)
-	}
-	return DistPath{basePath{path, ctx.Config(), ""}}
-}
-
-func (p DistPath) writablePath() {}
-
-func (p DistPath) Valid() bool {
-	return p.config.productVariables.DistDir != nil && *p.config.productVariables.DistDir != ""
-}
-
-func (p DistPath) String() string {
-	if !p.Valid() {
-		panic("Requesting an invalid path")
-	}
-	return filepath.Join(*p.config.productVariables.DistDir, p.path)
-}
-
-func (p DistPath) RelPathString() string {
-	return p.path
-}
-
 // ModuleSrcPath is a Path representing a file rooted from a module's local source dir
 type ModuleSrcPath struct {
 	SourcePath