[libc] [llvm] [libc] Remove UB specializations of type traits for `BigInt` (PR #84035)

[Nick Desaulniers via llvm-commits]

================
@@ -38,7 +38,8 @@ TestLogger &operator<<(TestLogger &logger, Location Loc) {
 // When the value is UInt128, __uint128_t or wider, show its hexadecimal
 // digits.
 template <typename T>
-cpp::enable_if_t<cpp::is_integral_v<T> && (sizeof(T) > sizeof(uint64_t)),
+cpp::enable_if_t<(cpp::is_integral_v<T> && (sizeof(T) > sizeof(uint64_t))) ||
+                     cpp::is_big_int_v<T>,
----------------
nickdesaulniers wrote:

Ok, I'll work on finishing cleaning up the todos from https://github.com/llvm/llvm-project/commit/48b0bc837085a38ff1de33010d9222363f70238f next week.

https://github.com/llvm/llvm-project/pull/84035