[clang] Lex: add support for `i128` and `ui128` suffixes (PR #130993)

[Mariya Podchishchaeva via cfe-commits]

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@@ -13,16 +13,24 @@ __int64 w = 0x43ui64;
 __int64 z = 9Li64;  // expected-error {{invalid suffix}}
 __int64 q = 10lli64;  // expected-error {{invalid suffix}}
 
-__complex double c1 = 1i;
-__complex double c2 = 1.0i;
+__complex double c1 = 1i; // GNU extension
+__complex double c2 = 1.0i; // GNU extension
 __complex float c3 = 1.0if;
 
+#define UINT128_MAX 0xffffffffffffffffffffffffffffffffui128
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Fznamznon wrote:

Maybe adding a test for `i128` suffix makes sense?

https://github.com/llvm/llvm-project/pull/130993