[VE] Rename VE toolchain source files

[kaz7]

Summary

Rename VE.cpp and VE.h to VEToolchain.cpp and VEToolchain.h respectively
in order to avoid link warning message. Linker warns that VE.cpp.o and
Arch/VE.cpp.o have the same name.

clang/lib/Driver/CMakeLists.txt

add_clang_library(clangDriver
   ToolChains/Myriad.cpp
   ToolChains/NaCl.cpp
   ToolChains/NetBSD.cpp
   ToolChains/OpenBSD.cpp
   ToolChains/PS4CPU.cpp
   ToolChains/RISCVToolchain.cpp
   ToolChains/Solaris.cpp
   ToolChains/TCE.cpp
-  ToolChains/VE.cpp
+  ToolChains/VEToolchain.cpp
   ToolChains/WebAssembly.cpp
   ToolChains/XCore.cpp
   ToolChains/PPCLinux.cpp
   ToolChains/InterfaceStubs.cpp
   Types.cpp
   XRayArgs.cpp
 
   DEPENDS
   ClangDriverOptions
 
   LINK_LIBS
   clangBasic
   ${system_libs}
   )

clang/lib/Driver/Driver.cpp

 #include "ToolChains/NaCl.h"
 #include "ToolChains/NetBSD.h"
 #include "ToolChains/OpenBSD.h"
 #include "ToolChains/PPCLinux.h"
 #include "ToolChains/PS4CPU.h"
 #include "ToolChains/RISCVToolchain.h"
 #include "ToolChains/Solaris.h"
 #include "ToolChains/TCE.h"
-#include "ToolChains/VE.h"
+#include "ToolChains/VEToolchain.h"
 #include "ToolChains/WebAssembly.h"
 #include "ToolChains/XCore.h"
 #include "clang/Basic/Version.h"
 #include "clang/Config/config.h"
 #include "clang/Driver/Action.h"
 #include "clang/Driver/Compilation.h"
 #include "clang/Driver/DriverDiagnostic.h"
 #include "clang/Driver/Job.h"

clang/lib/Driver/ToolChains/VEToolchain.cpp

 //===--- VE.cpp - VE ToolChain Implementations ------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
-#include "VE.h"
+#include "VEToolchain.h"
 #include "CommonArgs.h"
 #include "clang/Driver/Compilation.h"
 #include "clang/Driver/Driver.h"
 #include "clang/Driver/Options.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 #include <cstdlib> // ::getenv