[AMDGPU] Remove unused ClangBuiltin definition for fmed3

[foad]

Summary

__builtin_amdgcn_fmed3 is unused since the actual builtins are
defined by Clang and have a floating point type suffix, h or f.

[arsenm]

It's really unfortunate we don't have a way to give a list of builtins for an intrinsic with type mangling

[b-sumner]

The device library is using the builtin, so I assume the build will fail when this change lands.

[b-sumner]

Also, I see no median intrinsic described in the LLVM programming guide.

[arsenm]

In D143643#4115510, @b-sumner wrote:

The device library is using the builtin, so I assume the build will fail when this change lands.

This doesn’t change the builtin at all

[b-sumner]

In D143643#4115531, @arsenm wrote:

In D143643#4115510, @b-sumner wrote:

The device library is using the builtin, so I assume the build will fail when this change lands.

This doesn’t change the builtin at all

OK, sorry for the noise.

llvm/include/llvm/IR/IntrinsicsAMDGPU.td

DefaultAttrsIntrinsic<[llvm_v2i16_ty], [llvm_i32_ty, llvm_i32_ty],
     [IntrNoMem, IntrSpeculatable]
 >;
 
 def int_amdgcn_class : DefaultAttrsIntrinsic<
   [llvm_i1_ty], [llvm_anyfloat_ty, llvm_i32_ty],
   [IntrNoMem, IntrSpeculatable]
 >;
 
-def int_amdgcn_fmed3 : ClangBuiltin<"__builtin_amdgcn_fmed3">,
+def int_amdgcn_fmed3 :
   DefaultAttrsIntrinsic<[llvm_anyfloat_ty],
     [LLVMMatchType<0>, LLVMMatchType<0>, LLVMMatchType<0>],
     [IntrNoMem, IntrSpeculatable]
 >;
 
 def int_amdgcn_cubeid : ClangBuiltin<"__builtin_amdgcn_cubeid">,
   DefaultAttrsIntrinsic<[llvm_float_ty],
     [llvm_float_ty, llvm_float_ty, llvm_float_ty],