Made lldb_private::ArchSpec more generic so that it can take a mach-o cpu

type and sub-type, or an ELF e_machine value. Also added a generic CPU type
to the arch spec class so we can have a single arch definition that the LLDB
core code can use. Previously a lot of places in the code were using the
mach-o definitions from a macosx header file. 

Switches over to using "llvm/Support/MachO.h" for the llvm::MachO::XXX for the
CPU types and sub types for mach-o ArchSpecs. Added "llvm/Support/ELF.h" so 
we can use the "llvm::ELF::XXX" defines for the ELF ArchSpecs.

Got rid of all CPU_TYPE_ and CPU_SUBTYPE_ defines that were previously being
used in LLDB.

llvm-svn: 105806