Restrict linkersymbol builtin to object dialect of Yul

test/libsolidity/syntaxTests/inlineAssembly/linkersymbol_builtin.sol

@@ -0,0 +1,10 @@
+contract C {
+  function f() public pure {
+    assembly {
+      pop(linkersymbol("contract/library.sol:L"))
+    }
+  }
+}
+// ----
+// DeclarationError 4619: (67-79): Function not found.
+// TypeError 3950: (67-105): Expected expression to evaluate to one value, but got 0 values instead.

test/libsolidity/syntaxTests/inlineAssembly/linkersymbol_function.sol

@@ -0,0 +1,10 @@
+contract C {
+  function f() public pure {
+    assembly {
+      function linkersymbol(a) {}
+
+      linkersymbol("contract/library.sol:L")
+    }
+  }
+}
+// ----