First pass at basic i/o implementation

[Ramblurr]

This commit pulls in a minimal set if java.io.* classes from the android source. It also pulls in the required implementation files. Strategic commenting out and import replacements ensures that this compiles.

The java.io.* package and the associated libcore.io.* classes do much more than pure file i/o (e.g., sockets, pipes). I commented out much of that which we don't need (marked with the "needed?" TODO). If we decide we don't need much of that, we can delete it. Additionally, we can also probably delete the many stub Struct* classes

I also commented out some bits that we need to decide if we want to implement (marked with the "implement" TODO).

Finally, if we decide we don't want the BlockGuardOs functionality (see Libcore.java) we can get rif of the Os->SqlFsPosix abstraction later.

minimal set from java.io.*:

• FileDescriptor.java
• FileFilter.java
• FileInputStream.java
• File.java
• FilenameFilter.java
• FileOutputStream.java
• IOCipherActivity.java
• RandomAccessFile.java

Implementation helpers:

• ErrnoException.java
• IoBridge.java
• IoUtils.java
• Libcore.java
• Memory.java
• OsConstants.java
• Os.java
• SizeOf.java
• SqlFsPosix.java
• StructAddrinfo.java
• StructFlock.java
• StructGroupReq.java
• StructLinger.java
• StructPasswd.java
• StructPollfd.java
• StructStatFs.java
• StructStat.java
• StructTimeval.java
• StructUtsname.java

[n8fr8]

Great progress. Eager to review, so will take a look as soon as I can.