Fix operand extension validation to use ANY-of semantics

Same fix as the capability extension validation: grammar extension lists
for operands are alternatives (ANY suffices, not ALL). The operand
validation was checking each extension individually and failing on the
first one not satisfied.

Combine all extension sources and check if at least one is satisfied,
matching C++ HasAnyOfExtensions() behavior. This fixes validation of
decorations like PerPrimitiveNV which list both SPV_NV_mesh_shader
and SPV_EXT_mesh_shader as alternatives.

Author: LegNeato

rust/spirv-tools-core/src/validation/mod.rs

@@ -997,21 +997,23 @@ fn validate_instruction_requirements(
                     });
                 }
             }
-            for required_ext in operand.required_extensions() {
-                if !extension_satisfied(required_ext, extensions, target_version) {
-                    return Err(ValidationError::MissingOperandExtension {
-                        opcode: inst.class.opcode,
-                        operand_index: index,
-                        required_extension: ExtensionName::from(required_ext),
-                    });
-                }
-            }
-            for required_ext in grammar_required_extensions_for_operand(operand) {
-                if !extension_satisfied(required_ext, extensions, target_version) {
+            // Collect ALL extensions from all sources and check DISJUNCTIVELY
+            // (like C++ spirv-val's HasAnyOfExtensions).
+            // The grammar lists alternatives and you need AT LEAST ONE
+            // from the combined set.
+            let mut all_required_exts: Vec<&str> = Vec::new();
+            all_required_exts.extend(operand.required_extensions());
+            all_required_exts.extend(grammar_required_extensions_for_operand(operand));
+
+            if !all_required_exts.is_empty() {
+                let has_any = all_required_exts
+                    .iter()
+                    .any(|&ext| extension_satisfied(ext, extensions, target_version));
+                if !has_any {
                     return Err(ValidationError::MissingOperandExtension {
                         opcode: inst.class.opcode,
                         operand_index: index,
-                        required_extension: ExtensionName::from(required_ext),
+                        required_extension: ExtensionName::from(all_required_exts[0]),
                     });
                 }
             }