amd/common: Move ac_export_mrt_z to ac_llvm_build.

The aim of this commit is to keep ac_shader_util LLVM-free,
since we would like to use it in ACO later.

Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/amd/common/ac_llvm_build.h

@@ -740,6 +740,11 @@ LLVMValueRef ac_build_atomic_cmp_xchg(struct ac_llvm_context *ctx, LLVMValueRef
 				      LLVMValueRef cmp, LLVMValueRef val,
 				      const char *sync_scope);
 
+void
+ac_export_mrt_z(struct ac_llvm_context *ctx, LLVMValueRef depth,
+		LLVMValueRef stencil, LLVMValueRef samplemask,
+		struct ac_export_args *args);
+
 #ifdef __cplusplus
 }
 #endif