Enable tests.

test/libsolidity/semanticTests/abiEncoderV1/struct/struct_storage_ptr.sol

@@ -21,6 +21,8 @@ contract C {
 		return (r[2], s.x, a, b, c, d);
 	}
 }
+// ====
+// compileViaYul: also
 // ----
 // library: L
 // f() -> 8, 7, 1, 2, 7, 12

test/libsolidity/semanticTests/libraries/external_call_with_storage_mapping_parameter.sol

@@ -12,6 +12,8 @@ contract C {
         return L.f(x);
     }
 }
+// ====
+// compileViaYul: also
 // ----
 // library: L
 // g(uint256): 4 -> 16

test/libsolidity/semanticTests/types/mapping_contract_key_library.sol

@@ -16,6 +16,8 @@ contract test {
         L.set(table, k, v);
     }
 }
+// ====
+// compileViaYul: also
 // ----
 // library: L
 // get(address): 0 -> 0

test/libsolidity/semanticTests/types/mapping_enum_key_library_encoderV2.sol

@@ -19,6 +19,7 @@ contract test {
     }
 }
 // ====
+// compileViaYul: also
 // EVMVersion: >=byzantium
 // ----
 // library: L