[clang] [C2y] Support WG14 N3457, the __COUNTER__ macro (PR #162662)

[Aaron Ballman via cfe-commits]

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@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -verify -std=c2y -finitial-counter-value=2147483646 %s
----------------
AaronBallman wrote:

The driver logic automagically handles that for us:
```
F:\source\llvm-project>llvm\out\build\x64-Debug\bin\clang.exe -cc1 -finitial-counter-value=4294967296 -std=c2y -fsyntax-only clang\test\C\C2y\n3457_2.c
error: invalid integral value '4294967296' in '-finitial-counter-value=4294967296'
```

https://github.com/llvm/llvm-project/pull/162662