Separate InstallPath from OutputPath

Create a new type InstallPath that is similar to OutputPath to
differentiate intermediates output paths from installed output
paths.

RelPathString is a poorly defined, undocumented function that is
primarily used to get an install path relative to out/soong to
generate an equivalent install path for Make relative to $(OUT_DIR).
Move it to InstallPath for now, and fix the one remaining user on
OutputPath.

Add a method to create an NDK install path so that ndk_sysroot.go
doesn't have to do it manually with PathForOutput.

Bug: 141877526
Test: m checkbuild
Change-Id: I83c5a0bd1fd6c3dba8d3b6d20d039f64f353ddd5
diff --git a/java/dexpreopt.go b/java/dexpreopt.go
index 6214dac..db6b455 100644
--- a/java/dexpreopt.go
+++ b/java/dexpreopt.go
@@ -22,7 +22,7 @@
 type dexpreopter struct {
 	dexpreoptProperties DexpreoptProperties
 
-	installPath         android.OutputPath
+	installPath         android.InstallPath
 	uncompressedDex     bool
 	isSDKLibrary        bool
 	isTest              bool
@@ -94,7 +94,7 @@
 	return false
 }
 
-func odexOnSystemOther(ctx android.ModuleContext, installPath android.OutputPath) bool {
+func odexOnSystemOther(ctx android.ModuleContext, installPath android.InstallPath) bool {
 	return dexpreopt.OdexOnSystemOtherByName(ctx.ModuleName(), android.InstallPathToOnDevicePath(ctx, installPath), dexpreoptGlobalConfig(ctx))
 }