Refactor 'in_make' to mean Kati is not skipped.

In Nougat and before, Make wrote a marker file to indicate that
soong_build was invoked from Make to change certain behaviors of Soong
at build time.
https://cs.android.com/android/platform/superproject/+/android-7.1.2_r36:build/core/soong.mk;l=70-73;drc=ae18638b0406ad107b0882a02a13cdd8b92f2a4e

Things have changed, and now soong_build is invoked from soong_ui, which
supports a --skip-make configuration flag:
https://cs.android.com/android/platform/superproject/+/master:build/soong/ui/build/build.go;l=31-33;drc=680387bf1d3ce7cbc77f535be7c42cec411b1687

Thus, the various remnants of 'EmbeddedInMake' and 'inMake'
configuration are misleading, since soong_build is no longer invoked
from Make. This CL refactors all instances to actually mean that
Kati is enabled (not skipped with --skip-make), and will run after
soong_build finishes, so Kati-specific behavior like the AndroidMk
singleton should run.

Test: TH presubmit

Change-Id: I576ab8e54f99f5c8ddf9feaf9a828019b279e266

android/config.go

@@ -112,7 +112,9 @@ type config struct {
 	envDeps   map[string]string
 	envFrozen bool
 
-	inMake bool
+	// Changes behavior based on whether Kati runs after soong_build, or if soong_build
+	// runs standalone.
+	katiEnabled bool
 
 	captureBuild      bool // true for tests, saves build parameters for each module
 	ignoreEnvironment bool // true for tests, returns empty from all Getenv calls
@@ -390,9 +392,9 @@ func NewConfig(srcDir, buildDir string, moduleListFile string) (Config, error) {
 		return Config{}, err
 	}
 
-	inMakeFile := filepath.Join(buildDir, ".soong.in_make")
-	if _, err := os.Stat(absolutePath(inMakeFile)); err == nil {
-		config.inMake = true
+	KatiEnabledMarkerFile := filepath.Join(buildDir, ".soong.kati_enabled")
+	if _, err := os.Stat(absolutePath(KatiEnabledMarkerFile)); err == nil {
+		config.katiEnabled = true
 	}
 
 	targets, err := decodeTargetProductVariables(config)
@@ -619,8 +621,8 @@ func (c *config) EnvDeps() map[string]string {
 	return c.envDeps
 }
 
-func (c *config) EmbeddedInMake() bool {
-	return c.inMake
+func (c *config) KatiEnabled() bool {
+	return c.katiEnabled
 }
 
 func (c *config) BuildId() string {