Revert "Switch from Calculator to ExactCalculator"

Temporary revert to get TT builds in shape.

This reverts commit 846505dc35bb155c1c2cf54d407a946e8f732494.

Bug: 20745303
Change-Id: Id3455cba38b7aabaffa63c8531a6430f69897c6e
diff --git a/target/product/core.mk b/target/product/core.mk
index d453303..519dbb8 100644
--- a/target/product/core.mk
+++ b/target/product/core.mk
@@ -23,6 +23,7 @@
 PRODUCT_PACKAGES += \
     BasicDreams \
     Browser \
+    Calculator \
     Calendar \
     CalendarProvider \
     CaptivePortalLogin \
@@ -32,7 +33,6 @@
     DocumentsUI \
     DownloadProviderUi \
     Email \
-    ExactCalculator \
     Exchange2 \
     ExternalStorageProvider \
     FusedLocation \