Rename BuildDir and NinjaBuildDir.

These are just out/ and out/soong/ and the old names were quite
confusing.

Test: Presubmits.
Merged-In: Idd9ce3c38a259faabcc56f0cd3fdac8b289123b1
Merged-In: I334ab40c668d2a94536f3e63d5f1fa0b401388ac
Change-Id: Ib7c568c6a97701f2240c5e3f0f2ce67397819ac0
diff --git a/context.go b/context.go
index 3234fd7..0685148 100644
--- a/context.go
+++ b/context.go
@@ -102,7 +102,7 @@
 	globalRules     map[Rule]*ruleDef
 
 	// set during PrepareBuildActions
-	ninjaBuildDir      ninjaString // The builddir special Ninja variable
+	outDir             ninjaString // The builddir special Ninja variable
 	requiredNinjaMajor int         // For the ninja_required_version variable
 	requiredNinjaMinor int         // For the ninja_required_version variable
 	requiredNinjaMicro int         // For the ninja_required_version variable
@@ -388,7 +388,7 @@
 		globs:              make(map[globKey]pathtools.GlobResult),
 		fs:                 pathtools.OsFs,
 		finishedMutators:   make(map[*mutatorInfo]bool),
-		ninjaBuildDir:      nil,
+		outDir:             nil,
 		requiredNinjaMajor: 1,
 		requiredNinjaMinor: 7,
 		requiredNinjaMicro: 0,
@@ -2392,8 +2392,8 @@
 		deps = append(deps, depsModules...)
 		deps = append(deps, depsSingletons...)
 
-		if c.ninjaBuildDir != nil {
-			err := c.liveGlobals.addNinjaStringDeps(c.ninjaBuildDir)
+		if c.outDir != nil {
+			err := c.liveGlobals.addNinjaStringDeps(c.outDir)
 			if err != nil {
 				errs = []error{err}
 				return
@@ -3205,9 +3205,9 @@
 	}
 }
 
-func (c *Context) setNinjaBuildDir(value ninjaString) {
-	if c.ninjaBuildDir == nil {
-		c.ninjaBuildDir = value
+func (c *Context) setOutDir(value ninjaString) {
+	if c.outDir == nil {
+		c.outDir = value
 	}
 }
 
@@ -3399,9 +3399,9 @@
 	return targets, nil
 }
 
-func (c *Context) NinjaBuildDir() (string, error) {
-	if c.ninjaBuildDir != nil {
-		return c.ninjaBuildDir.Eval(c.globalVariables)
+func (c *Context) OutDir() (string, error) {
+	if c.outDir != nil {
+		return c.outDir.Eval(c.globalVariables)
 	} else {
 		return "", nil
 	}
@@ -3751,8 +3751,8 @@
 }
 
 func (c *Context) writeBuildDir(nw *ninjaWriter) error {
-	if c.ninjaBuildDir != nil {
-		err := nw.Assign("builddir", c.ninjaBuildDir.Value(c.pkgNames))
+	if c.outDir != nil {
+		err := nw.Assign("builddir", c.outDir.Value(c.pkgNames))
 		if err != nil {
 			return err
 		}