fix macOS build (following Projucer changes made in Windows, which removed /Applications/JUCE/modules from its headers). move JUCE headers under source control, so that Windows and macOS can both build against same version of JUCE. remove AUv3 target (I think it's an iOS thing, so it will never work with this macOS fluidsynth dylib).

modules/juce_opengl/opengl/juce_OpenGLHelpers.h

@@ -0,0 +1,75 @@
+/*
+  ==============================================================================
+
+   This file is part of the JUCE library.
+   Copyright (c) 2017 - ROLI Ltd.
+
+   JUCE is an open source library subject to commercial or open-source
+   licensing.
+
+   By using JUCE, you agree to the terms of both the JUCE 5 End-User License
+   Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
+   27th April 2017).
+
+   End User License Agreement: www.juce.com/juce-5-licence
+   Privacy Policy: www.juce.com/juce-5-privacy-policy
+
+   Or: You may also use this code under the terms of the GPL v3 (see
+   www.gnu.org/licenses).
+
+   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
+   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
+   DISCLAIMED.
+
+  ==============================================================================
+*/
+
+namespace juce
+{
+
+//==============================================================================
+/**
+    A set of miscellaneous openGL helper functions.
+
+    @tags{OpenGL}
+*/
+class JUCE_API  OpenGLHelpers
+{
+public:
+    /** Clears the GL error state. */
+    static void resetErrorState();
+
+    /** Returns true if the current thread has an active OpenGL context. */
+    static bool isContextActive();
+
+    /** Clears the current context using the given colour. */
+    static void clear (Colour colour);
+
+    static void enableScissorTest (Rectangle<int> clip);
+
+    /** Checks whether the current context supports the specified extension. */
+    static bool isExtensionSupported (const char* extensionName);
+
+    /** Returns the address of a named GL extension function */
+    static void* getExtensionFunction (const char* functionName);
+
+    /** Makes some simple textual changes to a shader program to try to convert old GLSL
+        keywords to their v3 equivalents.
+
+        Before doing this, the function will check whether the current context is actually
+        using a later version of the language, and if not it will not make any changes.
+        Obviously this is not a real parser, so will only work on simple code!
+    */
+    static String translateVertexShaderToV3 (const String&);
+
+    /** Makes some simple textual changes to a shader program to try to convert old GLSL
+        keywords to their v3 equivalents.
+
+        Before doing this, the function will check whether the current context is actually
+        using a later version of the language, and if not it will not make any changes.
+        Obviously this is not a real parser, so will only work on simple code!
+    */
+    static String translateFragmentShaderToV3 (const String&);
+};
+
+} // namespace juce