Revert "public check method, needed for stephencelis#389"

This reverts commit bb3b705.

Author: jberkel

SQLite/Core/Connection.swift

@@ -651,7 +651,7 @@ public final class Connection {
         return success!
     }
 
-    @discardableResult public func check(_ resultCode: Int32, statement: Statement? = nil) throws -> Int32 {
+    @discardableResult func check(_ resultCode: Int32, statement: Statement? = nil) throws -> Int32 {
         guard let error = Result(errorCode: resultCode, connection: self, statement: statement) else {
             return resultCode
         }

SQLiteTests/ConnectionTests.swift

@@ -340,11 +340,4 @@ class ConnectionTests : SQLiteTestCase {
         AssertThrows(try stmt.run())
     }
 
-    func test_check_with_successCode_returnsCode() {
-        try! XCTAssertEqual(SQLITE_OK, db.check(SQLITE_OK))
-    }
-
-    func test_check_with_errorCode_throws() {
-        XCTAssertThrowsError(try db.check(SQLITE_CONSTRAINT))
-    }
 }