Don't append build directory to the output path twice.

Soong already uses build directory as a part of the generated output
path. Besides, trying to append it second time breaks if the build
directory is an absolute path.

Test: frameworks/rs/build_rs.py  (uses absolute build directory path)
Test: walleye-userdebug boots

Bug: 152235239
Change-Id: Ie03c9e688013b9a3e6bc859c936d89c538ded76a
Merged-In: Ie03c9e688013b9a3e6bc859c936d89c538ded76a
(cherry picked from commit f798c3ec32535ae3df58499daa66b56fb4167a57)
diff --git a/dexpreopt/dexpreopt.go b/dexpreopt/dexpreopt.go
index 02e54b3..0e1bfc6 100644
--- a/dexpreopt/dexpreopt.go
+++ b/dexpreopt/dexpreopt.go
@@ -589,7 +589,7 @@
 // at that time (Soong processes the jars in dependency order, which may be different from the
 // the system server classpath order).
 func SystemServerDexJarHostPath(ctx android.PathContext, jar string) android.OutputPath {
-	return android.PathForOutput(ctx, ctx.Config().BuildDir(), "system_server_dexjars", jar+".jar")
+	return android.PathForOutput(ctx, "system_server_dexjars", jar+".jar")
 }
 
 func contains(l []string, s string) bool {