[clang] [NFC] Move warning from CodeGen to Sema. (PR #107397)

[Zahira Ammarguellat via cfe-commits]

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@@ -21,6 +25,7 @@ void a() {
   EVALF((2. + 3i) + (4. + 5i), 6. + 8i);
   EVALF((2. + 3i) - (4. + 5i), -2. - 2i);
   EVALF((2. + 3i) * (4. + 5i), -7. + 22i);
+  // div-precision-warning at +1 {{excess precision is requested but the target does not support excess precision which may result in observable differences in arithmetic behavior ,additional use of 'long double' were found but not diagnosed}}
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zahiraam wrote:

We may want to edit the diagnostic and edit this:
`additional use of`
to
`additional use of requested higher precision`
WDYT?

https://github.com/llvm/llvm-project/pull/107397