Revert "Use cp instead of install for ndk_headers"

This reverts commit 1202729cb215ea039306a2e2b88eddaff20b73cd.

Reason for revert: Breaks aosp-main/ndk builds

Change-Id: I453792f7f974dc336d5f6775adfc5899b8d34d7b
diff --git a/android/paths.go b/android/paths.go
index a40f482..61c1258 100644
--- a/android/paths.go
+++ b/android/paths.go
@@ -1831,13 +1831,17 @@
 	return base.Join(ctx, pathComponents...)
 }
 
-func PathForNdkInstall(ctx PathContext, paths ...string) OutputPath {
-	return PathForOutput(ctx, append([]string{"ndk"}, paths...)...)
+func pathForNdkOrSdkInstall(ctx PathContext, prefix string, paths []string) InstallPath {
+	base := pathForPartitionInstallDir(ctx, "", prefix, false)
+	return base.Join(ctx, paths...)
+}
+
+func PathForNdkInstall(ctx PathContext, paths ...string) InstallPath {
+	return pathForNdkOrSdkInstall(ctx, "ndk", paths)
 }
 
 func PathForMainlineSdksInstall(ctx PathContext, paths ...string) InstallPath {
-	base := pathForPartitionInstallDir(ctx, "", "mainline-sdks", false)
-	return base.Join(ctx, paths...)
+	return pathForNdkOrSdkInstall(ctx, "mainline-sdks", paths)
 }
 
 func InstallPathToOnDevicePath(ctx PathContext, path InstallPath) string {