Increase page sizes on Android platforms to 16KB

Add compiler flags to the Android platform targets that increase the
page size to 16KB. This will be required by the Google Play Store
starting in October.
This change only affects the android platform artifacts.

Fixes #819

Author: ReneeVandervelde

bdk-ffi/.cargo/config.toml

@@ -0,0 +1,8 @@
+[target.'cfg(target_os = "android")']
+rustflags = [
+    "-C", "link-arg=-z",
+    "-C", "link-arg=max-page-size=16384",
+    "-C", "link-arg=-z",
+    "-C", "link-arg=common-page-size=16384",
+]
+