shader_recompiler: GCC fixes

Fixes members of unnamed union not being accessible, and one function
without a declaration.

src/shader_recompiler/frontend/ir/abstract_syntax_list.h

@@ -13,10 +13,6 @@ namespace Shader::IR {
 class Block;
 
 struct AbstractSyntaxNode {
-    struct NonTrivialDummy {
-        NonTrivialDummy() {}
-    };
-
     enum class Type {
         Block,
         If,
@@ -27,9 +23,7 @@ struct AbstractSyntaxNode {
         Return,
         Unreachable,
     };
-    Type type{};
-    union {
-        NonTrivialDummy dummy{};
+    union Data {
         Block* block;
         struct {
             U1 cond;
@@ -55,6 +49,9 @@ struct AbstractSyntaxNode {
             Block* skip;
         } break_node;
     };
+
+    Data data{};
+    Type type{};
 };
 using AbstractSyntaxList = std::vector<AbstractSyntaxNode>;
 

src/shader_recompiler/frontend/ir/post_order.cpp

@@ -20,7 +20,7 @@ BlockList PostOrder(const AbstractSyntaxNode& root) {
     if (root.type != AbstractSyntaxNode::Type::Block) {
         throw LogicError("First node in abstract syntax list root is not a block");
     }
-    Block* const first_block{root.block};
+    Block* const first_block{root.data.block};
     visited.insert(first_block);
     block_stack.push_back(first_block);