Restore UNSAFE_DISABLE_HIDDENAPI_FLAGS functionality.

It got broken with the move to hiddenapi to Soong.

Test: UNSAFE_DISABLE_HIDDENAPI_FLAGS=true m -j32
Change-Id: Id369bfae8e118907b1f12faa7e4207494904edda
diff --git a/java/java.go b/java/java.go
index 49095ca..209d0a7 100644
--- a/java/java.go
+++ b/java/java.go
@@ -1180,15 +1180,17 @@
 		}
 
 		// Hidden API CSV generation and dex encoding
-		isBootJar := inList(ctx.ModuleName(), ctx.Config().BootJars())
-		if isBootJar || inList(ctx.ModuleName(), ctx.Config().HiddenAPIExtraAppUsageJars()) {
-			// Derive the greylist from classes jar.
-			hiddenAPIGenerateCSV(ctx, j.implementationJarFile)
-		}
-		if isBootJar {
-			hiddenAPIJar := android.PathForModuleOut(ctx, "hiddenapi", jarName)
-			hiddenAPIEncodeDex(ctx, hiddenAPIJar, dexOutputFile)
-			dexOutputFile = hiddenAPIJar
+		if !ctx.Config().IsEnvTrue("UNSAFE_DISABLE_HIDDENAPI_FLAGS") {
+			isBootJar := inList(ctx.ModuleName(), ctx.Config().BootJars())
+			if isBootJar || inList(ctx.ModuleName(), ctx.Config().HiddenAPIExtraAppUsageJars()) {
+				// Derive the greylist from classes jar.
+				hiddenAPIGenerateCSV(ctx, j.implementationJarFile)
+			}
+			if isBootJar {
+				hiddenAPIJar := android.PathForModuleOut(ctx, "hiddenapi", jarName)
+				hiddenAPIEncodeDex(ctx, hiddenAPIJar, dexOutputFile)
+				dexOutputFile = hiddenAPIJar
+			}
 		}
 
 		// merge dex jar with resources if necessary