Assume liba52 is built as fixed-point if needed

(This kinda sucks, but liba52 does not export is build mode through
 any public header)

modules/audio_filter/converter/a52tofloat32.c

@@ -33,9 +33,13 @@
 
 #include <vlc_common.h>
 #include <vlc_plugin.h>
+#include <vlc_cpu.h>
 
 #include <stdint.h>                                         /* int16_t .. */
 
+#if !HAVE_FPU
+# define LIBA52_FIXED
+#endif
 #ifdef USE_A52DEC_TREE                                 /* liba52 header file */
 #   include "include/a52.h"
 #else