Define ABIFLAGS as an empty string

* This adds the 'abiflags' attribute to the sys module

Change-Id: I0c3b7d48f5168392b1cec0307105d88e1f6f38b0
diff --git a/Android.bp b/Android.bp
index 0e41bf4..ed4d209 100644
--- a/Android.bp
+++ b/Android.bp
@@ -222,11 +222,13 @@
         linux: {
             cflags: [
                 "-DPLATFORM=\"linux\"",
+                "-DABIFLAGS=\"\"",
             ],
         },
         darwin_x86_64: {
             cflags: [
                 "-DPLATFORM=\"darwin\"",
+                "-DABIFLAGS=\"\"",
             ],
         },
     },