Canonicalise Windows target triple spellings

Description

Canonicalise Windows target triple spellings

Construct a uniform Windows target triple nomenclature which is congruent to the
Linux counterpart. The old triples are normalised to the new canonical form.
This cleans up the long-standing issue of odd naming for various Windows
environments.

There are four different environments on Windows:

MSVC: The MS ABI, MSVCRT environment as defined by Microsoft
GNU: The MinGW32/MinGW32-W64 environment which uses MSVCRT and auxiliary libraries
Itanium: The MSVCRT environment + libc++ built with Itanium ABI
Cygnus: The Cygwin environment which uses custom libraries for everything

The following spellings are now written as:

i686-pc-win32 => i686-pc-windows-msvc
i686-pc-mingw32 => i686-pc-windows-gnu
i686-pc-cygwin => i686-pc-windows-cygnus

This should be sufficiently flexible to allow us to target other windows
environments in the future as necessary.

Details

Auditors
grosbach
H23 MC code reviews Triggered Audit
Committed
compnerdMar 27 2014, 3:50 PM
Parents
rL204976: [PowerPC] Don't remove self VSX copies in PPCInstrInfo::copyPhysReg
Branches
Unknown
Tags
Unknown