Make autoload dynamically dispatch to require. Fixes #5403.

core/src/main/java/org/jruby/runtime/load/LoadService.java

@@ -406,7 +406,7 @@ public boolean require(String requireName) {
     }
 
     public boolean autoloadRequire(String requireName) {
-        return smartLoadInternal(requireName, false) != RequireState.CIRCULAR;
+        return runtime.getTopSelf().callMethod(runtime.getCurrentContext(), "require", runtime.newString(requireName)).isTrue();
     }
 
     private enum RequireState {

spec/tags/ruby/core/kernel/autoload_tags.txt

@@ -1,9 +1,8 @@
 fails:Kernel.autoload sets the autoload constant in Object's constant table
-fails:Kernel#autoload registers a file to load the first time the named constant is accessed
 fails:Kernel#autoload? returns the name of the file that will be autoloaded
 fails:Kernel#autoload when called from included module's method setups the autoload on the included module
 fails:Kernel#autoload when called from included module's method the autoload relative to the included module works
 fails:Kernel.autoload when called from included module's method setups the autoload on the included module
 fails:Kernel.autoload when called from included module's method the autoload is reacheable from the class too
 fails:Kernel.autoload when called from included module's method the autoload relative to the included module works
-fails:Kernel#autoload calls main.require(path) to load the file
+fails:Kernel#autoload registers a file to load the first time the named constant is accessed

test/mri/excludes/TestAutoload.rb

@@ -1,3 +1,2 @@
 exclude :test_autoload_while_autoloading, "needs investigation"
 exclude :test_bug_13526, "racey test that doesn't behave as expected with concurrent threads #5294"
-exclude :test_require_implemented_in_ruby_is_called, "attempted to dispatch to require but it seems to recursively call itself"