Remove unused StructLiteralExp::constType variable.

dmd2/expression.c

@@ -4368,7 +4368,6 @@ StructLiteralExp::StructLiteralExp(Loc loc, StructDeclaration *sd, Expressions *
     this->ownedByCtfe = false;
     this->ctorinit = 0;
 #if IN_LLVM
-    constType = NULL;
     this->inProgressMemory = NULL;
     this->globalVar = NULL;
 #endif

dmd2/expression.h

@@ -635,7 +635,6 @@ struct StructLiteralExp : Expression
     llvm::Value* inProgressMemory;
 
     llvm::Constant *toConstElem(IRState *irs);
-    llvm::StructType *constType;
     // A global variable for taking the address of this struct literal constant,
     // if it already exists. Used to resolve self-references.
     llvm::GlobalVariable *globalVar;