v.gen: add _M_ARM64 to endianness check

[daddycocoaman]

This PR addresses #21003 by adding a check that will allow for Windows ARM64 users to compile the X64 version of V with .\make.bat -msvc . The only remaining issue is that there is a harmless but loud error that shows up from detect_tcc because TCC is downloaded even when another compiler is specified (which maybe shouldn't be the case?). But everything works:

Updating TCC
 > Syncing TCC from https://github.com/vlang/tccbin

Updating vc...
 > Sync with remote https://github.com/vlang/vc

Building V...
 > Attempting to build "./v_win_bootstrap.exe" (from v_win.c) with MSVC
v_win.c
 > Compiling "./v.exe" with "./v_win_bootstrap.exe"
> C compiler cmd: "C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.39.33519\bin\Hostx64\x64\cl.exe" "@C:\Users\*\AppData\Local\Temp\v_0\v_up.exe.tmp.c.rsp"
> C compiler response file "C:\Users\*\AppData\Local\Temp\v_0\v_up.exe.tmp.c.rsp":
-w /we4013 /volatile:ms /Fo"C:\Users\*\AppData\Local\Temp\v_0\v_up.exe.tmp.c.obj" /F 16777216 /MDd /D_DEBUG /Zi /Fd"C:\Users\*\AppData\Local\Temp\v_0\v_up.exe.tmp.c.pdb" "C:\Users\*\AppData\Local\Temp\v_0\v_up.exe.tmp.c" -I "C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\ucrt" -I "C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.39.33519\include" -I "C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\um" -I "C:\Program Files (x86)\Windows Kits\10\Include\10.0.22621.0\shared" -I "C:\Users\*\dev\v-dev\thirdparty\stdatomic\win" kernel32.lib user32.lib advapi32.lib ws2_32.lib dbghelp.lib ws2_32.lib advapi32.lib shell32.lib /link /NOLOGO /OUT:"C:\Users\*\dev\v-dev\v_up.exe" /LIBPATH:"C:\Program Files (x86)\Windows Kits\10\Lib\10.0.22621.0\ucrt\X64" /LIBPATH:"C:\Program Files (x86)\Windows Kits\10\Lib\10.0.22621.0\um\X64" /LIBPATH:"C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.39.33519\lib\X64" /DEBUG:FULL
==================
C:/Users/*/AppData/Local/Temp/v_0/detect_tcc.01HSYEXNM7BRXKQF38GTJMN8XC.tmp.c:6895: warning: implicit declaration of function 'tcc_backtrace'
tcc: error: unrecognized file type
tcc: error: library 'dbghelp' not found
...
==================
(Use `v -cg` to print the entire error message)

builder error:
==================
C error. This should never happen.

This is a compiler bug, please report it using `v bug file.v`.

https://github.com/vlang/v/issues/new/choose

You can also use #help on Discord: https://discord.gg/vlang

 > V built successfully
 > To add V to your PATH, run `./v.exe symlink`.

V version: V 0.4.5 80a4249

[JalonSolov]

Yes, tcc should still be downloaded... if there were a proper Windows ARM64 version of tcc.

The reason is that .\make.bat -msvc only builds V itself with msvc, it doesn't force everything built with V to be built the same. To do that, you would have to set VFLAGS='-cc msvc' or just let the normal "rollover" to msvc happen when a working tcc can't be found - which is slower than setting the env var so it doesn't try tcc at all.

tcc is so much faster than msvc that it will always be the default... unless we replace it with vtcc (the V port of tcc).