ARM: check struct offsets only when they are used

The offsets differ depending on configuration, so only check them when
they will actually be used.  Presently, this is when NEON is enabled.

Originally committed as revision 23436 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/arm/mpegvideo_arm.c

@@ -24,12 +24,14 @@
 #include "mpegvideo_arm.h"
 #include "asm-offsets.h"
 
+#if HAVE_NEON
 CHK_OFFS(MpegEncContext, y_dc_scale,       Y_DC_SCALE);
 CHK_OFFS(MpegEncContext, c_dc_scale,       C_DC_SCALE);
 CHK_OFFS(MpegEncContext, ac_pred,          AC_PRED);
 CHK_OFFS(MpegEncContext, block_last_index, BLOCK_LAST_INDEX);
 CHK_OFFS(MpegEncContext, inter_scantable.raster_end, INTER_SCANTAB_RASTER_END);
 CHK_OFFS(MpegEncContext, h263_aic,         H263_AIC);
+#endif
 
 void ff_dct_unquantize_h263_inter_neon(MpegEncContext *s, DCTELEM *block,
                                        int n, int qscale);