[llvm] [SPIR-V] Support SPV_INTEL_fp_max_error extension for `!fpmath` metadata (PR #130619)

[Viktoria Maximova via llvm-commits]

================
@@ -307,6 +309,10 @@ SPIR-V backend, along with their descriptions and argument details.
      - None
      - `[Type, 32-bit Integer, Metadata]`
      - Assigns one of two memory aliasing decorations (specified by the second argument) to instructions using original aliasing metadata node. Not emitted directly but used to support SPIR-V representation in LLVM IR.
+   * - `int_spv_assign_fpmaxerror_decoration`
----------------
vmaksimo wrote:

I believe FP-Math flags are not the same as `!fpmath` metadata. I've added intrinsic to support the second case, but we can extend the extension usage to support your case too (we didn't have such support in Khronos though)

https://github.com/llvm/llvm-project/pull/130619