Recovery partition has same layout as system

Recovery partition has same layout as system. In other words,
executables are installed to <recovery_root>/system/bin and libs are
installed to ../system/lib.

This is made possible because the recovery partition is now
self-contained, i.e., shell, adbd, etc. are hosted in the recovery
partition and thus we no longer has to mount the real system.img
to /system. So /system is now available to executables built for
recovery mode.

Bug: 63673171
Test: `adb reboot recovery; adb devices` shows the device ID
Test: Select 'mount /system' in the recovery mode, then `adb shell`.
$ lsof -p `pidof adbd` shows that libm.so, libc.so, etc. are loaded from
the /lib directory.

Change-Id: I6c4f903ad21fd3dd10a07c4588be85d3d678c099

android/paths.go

@@ -950,7 +950,8 @@ func PathForModuleInstall(ctx ModuleInstallPathContext, pathComponents ...string
 		if ctx.InstallInData() {
 			partition = "data"
 		} else if ctx.InstallInRecovery() {
-			partition = "recovery/root"
+			// the layout of recovery partion is the same as that of system partition
+			partition = "recovery/root/system"
 		} else if ctx.SocSpecific() {
 			partition = ctx.DeviceConfig().VendorPath()
 		} else if ctx.DeviceSpecific() {

cc/binary.go

@@ -357,11 +357,6 @@ func (binary *binaryDecorator) link(ctx ModuleContext,
 }
 
 func (binary *binaryDecorator) install(ctx ModuleContext, file android.Path) {
-	// <recovery>/bin is a symlink to /system/bin. Recovery binaries are all in /sbin.
-	if ctx.inRecovery() {
-		binary.baseInstaller.dir = "sbin"
-	}
-
 	binary.baseInstaller.install(ctx, file)
 	for _, symlink := range binary.Properties.Symlinks {
 		binary.symlinks = append(binary.symlinks,