Working codec2 support

libs/libcodec2/src/four1.h

@@ -0,0 +1,18 @@
+/*---------------------------------------------------------------------------*\
+  
+  FILE........: four1.h
+  AUTHOR......: David Rowe
+  DATE CREATED: 20/2/95
+
+  Numerical Recipies in C FFT function.  I have a nasty licence so please
+  replace me.
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef __FOUR1__
+#define __FOUR1__
+
+void four1(float x[], int n, int isign);
+
+#endif	/* __FOUR1__ */
+