Remove TEMPORARY_DISABLE_PATH_RESTRICTIONS

This was a temporary migration tool, and has been broken ever since the
ninja environment started being restricted. Remove it, since it has
lasted two releases.

Test: TEMPORARY_DISABLE_PATH_RESTRICTIONS=true m
Change-Id: I2e3709525598030f5c24d12fa966e531dfed33ae
diff --git a/ui/build/path.go b/ui/build/path.go
index c34ba1b..7122927 100644
--- a/ui/build/path.go
+++ b/ui/build/path.go
@@ -177,9 +177,12 @@
 		execs = append(execs, parsePathDir(pathEntry)...)
 	}
 
-	allowAllSymlinks := config.Environment().IsEnvTrue("TEMPORARY_DISABLE_PATH_RESTRICTIONS")
+	if config.Environment().IsEnvTrue("TEMPORARY_DISABLE_PATH_RESTRICTIONS") {
+		ctx.Fatalln("TEMPORARY_DISABLE_PATH_RESTRICTIONS was a temporary migration method, and is now obsolete.")
+	}
+
 	for _, name := range execs {
-		if !paths.GetConfig(name).Symlink && !allowAllSymlinks {
+		if !paths.GetConfig(name).Symlink {
 			continue
 		}