While building against this level in general would break our app on
older systems, the NDK will automatically use this level for 64-bit
ABI builds (which are not supported in older levels). So to build
against 64-bit ABIs we have to support this API level.
In Java all integer types are signed, when a negative integer is casted
to a larger type (e.g. int to long) then due to sign extension the upper
bytes are not 0. So writing that value to a byte array does not produce
the expected result. By overloading the putX() methods we make sure to
upcast the values correctly.