Ensure framework-oahl-backward-compatibility is installed

Change made in response to comments on
I17170f873eec93b2e2ed7be3459e2d28c96bbe4c.

Bug: 18027885
Bug: 72375096
Test: build, flash and test manually and with FrameworkCoreTests
Change-Id: I18020c495bd4f0a4a6f700edd44c2f4e7cf67826
diff --git a/target/product/base.mk b/target/product/base.mk
index 4356c97..88b21c4 100644
--- a/target/product/base.mk
+++ b/target/product/base.mk
@@ -141,6 +141,12 @@
     vold \
     wm
 
+# Add the compatibility library that is needed when org.apache.http.legacy
+# is removed from the bootclasspath.
+ifeq ($(REMOVE_OAHL_FROM_BCP),true)
+PRODUCT_PACKAGES += framework-oahl-backward-compatibility
+endif
+
 # Essential HAL modules
 PRODUCT_PACKAGES += \
     android.hardware.cas@1.0-service \