Use the min sdk version from soong.

Test: make checkbuild
Bug: None
Change-Id: I0306803cebf98748503b7e217db0f0f5959bf4f7
diff --git a/core/binary.mk b/core/binary.mk
index 6d6b6a9..c7be2a4 100644
--- a/core/binary.mk
+++ b/core/binary.mk
@@ -104,7 +104,7 @@
   ifneq (,$(filter arm64 mips64 x86_64,$(my_arch)))
     my_min_sdk_version := 21
   else
-    my_min_sdk_version := 9
+    my_min_sdk_version := $(MIN_SUPPORTED_SDK_VERSION)
   endif
 
   # Historically we've just set up a bunch of symlinks in prebuilts/ndk to map