Fix missing NEON registers for the 'register read' command with the lldb...

Fix missing NEON registers for the 'register read' command with the lldb debugserver which supports the 'qRegisterInfo' packet
that dynamically discovers remote register context information.

o GDBRemoteRegisterContext.h:

Change the prototype of HardcodeARMRegisters() to take a boolean flag, which now becomes

    void
    HardcodeARMRegisters(bool from_scratch);

o GDBRemoteRegisterContext.cpp:

HardcodeARMRegisters() now checks the from_scratch flag and decides whether to add composite registers to the already
existing primordial registers based on a table called g_composites which describes the composite registers.

o ProcessGDBRemote.cpp:

Modify the logic of ProcessGDBRemote::BuildDynamicRegisterInfo() to call m_register_info.HardcodeARMRegisters()
with the newly introduced 'bool from_scrach' flag.

rdar://problem/10652076

llvm-svn: 156773