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_dsp/frequency/juce_FFT.h

@@ -0,0 +1,122 @@
+/*
+  ==============================================================================
+
+   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
+{
+namespace dsp
+{
+
+/**
+    Performs a fast fourier transform.
+
+    This is only a simple low-footprint implementation and isn't tuned for speed - it may
+    be useful for simple applications where one of the more complex FFT libraries would be
+    overkill. (But in the future it may end up becoming optimised of course...)
+
+    The FFT class itself contains lookup tables, so there's some overhead in creating
+    one, you should create and cache an FFT object for each size/direction of transform
+    that you need, and re-use them to perform the actual operation.
+
+    @tags{DSP}
+*/
+class JUCE_API  FFT
+{
+public:
+    //==============================================================================
+    /** Initialises an object for performing forward and inverse FFT with the given size.
+        The number of points the FFT will operate on will be 2 ^ order.
+    */
+    FFT (int order);
+
+    /** Destructor. */
+    ~FFT();
+
+    //==============================================================================
+    /** Performs an out-of-place FFT, either forward or inverse.
+        The arrays must contain at least getSize() elements.
+    */
+    void perform (const Complex<float>* input, Complex<float>* output, bool inverse) const noexcept;
+
+    /** Performs an in-place forward transform on a block of real data.
+
+        As the coefficients of the negative frequences (frequencies higher than
+        N/2 or pi) are the complex conjugate of their positive counterparts,
+        it may not be necessary to calculate them for your particular application.
+        You can use dontCalculateNegativeFrequencies to let the FFT
+        engine know that you do not plan on using them. Note that this is only a
+        hint: some FFT engines (currently only the Fallback engine), will still
+        calculate the negative frequencies even if dontCalculateNegativeFrequencies
+        is true.
+
+        The size of the array passed in must be 2 * getSize(), and the first half
+        should contain your raw input sample data. On return, if
+        dontCalculateNegativeFrequencies is false, the array will contain size
+        complex real + imaginary parts data interleaved. If
+        dontCalculateNegativeFrequencies is true, the array will contain at least
+        (size / 2) + 1 complex numbers. Both outputs can be passed to
+        performRealOnlyInverseTransform() in order to convert it back to reals.
+    */
+    void performRealOnlyForwardTransform (float* inputOutputData,
+                                          bool dontCalculateNegativeFrequencies = false) const noexcept;
+
+    /** Performs a reverse operation to data created in performRealOnlyForwardTransform().
+
+        Although performRealOnlyInverseTransform will only use the first ((size / 2) + 1)
+        complex numbers, the size of the array passed in must still be 2 * getSize(), as some
+        FFT engines require the extra space for the calculation. On return, the first half of the
+        array will contain the reconstituted samples.
+    */
+    void performRealOnlyInverseTransform (float* inputOutputData) const noexcept;
+
+    /** Takes an array and simply transforms it to the magnitude frequency response
+        spectrum. This may be handy for things like frequency displays or analysis.
+        The size of the array passed in must be 2 * getSize().
+    */
+    void performFrequencyOnlyForwardTransform (float* inputOutputData) const noexcept;
+
+    /** Returns the number of data points that this FFT was created to work with. */
+    int getSize() const noexcept            { return size; }
+
+    //==============================================================================
+   #ifndef DOXYGEN
+    /* internal */
+    struct Instance;
+    template <typename> struct EngineImpl;
+   #endif
+
+private:
+    //==============================================================================
+    struct Engine;
+
+    std::unique_ptr<Instance> engine;
+    int size;
+
+    //==============================================================================
+    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (FFT)
+};
+
+} // namespace dsp
+} // namespace juce