Fix r195149. Triple should correctly reflect that target. If it contains ios,
e.g. thumbv7m-apple-ios3.0.0-eabi, then it should mean it's an iOS target. For
embedded targets, the OS should be unknown, e.g. thumbv7m-apple-unknown-macho.
Since Tim has recently fixed the triple, r195149 is no longer needed.
rdar://15911035
[ELF] Dont include all targets
[ELF] Rename File.h to ELFFile.h to avoid confusion.

No change in functionality.
Add a XCoreTargetStreamer and port over the simple uses of EmitRawText.
[ELF] Separate implementation from the class declaration.

ELFFile would be a class that rest of the targets would derive from.
To keep the implementation clean, separate the implementation from
rest of the Header file.
Add missing file.
Use emitRawComment instead of EmitRawText.
Add back spaces I missed in the conversion to emitRawComments.

Sorry about that.
[ELF] Unify interfaces between DynamicFile/ELFFile.
[ELF] Separate ELFReader classes for subclassing
Remove dead code.
[ELF] Add Target specific Readers.

No change in functionality.