Fixes for MInts (#1107)

There existed several bugs leading to crashes when the LLVM backend
compiles certain definitions containing the MInt sort. This PR contains
a regression test and the fixes needed to make that test pass, namely:

* Don't emit a case for `evaluate_function_symbol` if the function has a
variable return sort (only happens with functions that have a sort
variable in the return sort that does not appear in the argument list)
* Fix a case where a string literal did not get its initializer set in
all cases.

lib/codegen/EmitConfigParser.cpp

@@ -207,6 +207,9 @@ static void emit_data_for_symbol(
     if (is_eval && !is_func) {
       continue;
     }
+    if (is_eval && !symbol->get_sort()->is_concrete()) {
+      continue;
+    }
     auto *case_block
         = llvm::BasicBlock::Create(ctx, "tag" + std::to_string(tag), func);
     auto *branch = llvm::BranchInst::Create(merge_block, case_block);
@@ -1310,8 +1313,13 @@ static void emit_return_sort_table(kore_definition *def, llvm::Module *mod) {
     auto *char_type = llvm::Type::getInt8Ty(ctx);
     auto *str_type = llvm::ArrayType::get(char_type, sort_str.size() + 1);
 
+    auto *str = llvm::ConstantDataArray::getString(ctx, sort_str, true);
     auto *sort_name
         = module->getOrInsertGlobal("sort_name_" + sort_str, str_type);
+    auto *global_var = llvm::cast<llvm::GlobalVariable>(sort_name);
+    if (!global_var->hasInitializer()) {
+      global_var->setInitializer(str);
+    }
 
     auto *i64_type = llvm::Type::getInt64Ty(ctx);
     auto *zero = llvm::ConstantInt::get(i64_type, 0);