GUI: try using FFTW for per-chan osc wave center

not reliable yet

extern/fftw/kernel/align.c

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2003, 2007-14 Matteo Frigo
+ * Copyright (c) 2003, 2007-14 Massachusetts Institute of Technology
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+
+#include "kernel/ifftw.h"
+
+#if HAVE_SIMD
+#  define ALGN 16
+#else
+   /* disable the alignment machinery, because it will break,
+      e.g., if sizeof(R) == 12 (as in long-double/x86) */
+#  define ALGN 0
+#endif
+
+/* NONPORTABLE */
+int X(ialignment_of)(R *p)
+{
+#if ALGN == 0
+     UNUSED(p);
+     return 0;
+#else
+     return (int)(((uintptr_t) p) % ALGN);
+#endif
+}