Fix compilation with --disable-everything --enable-encoder=flac.

libavcodec/flacdsp.c

@@ -128,6 +128,6 @@ av_cold void ff_flacdsp_init(FLACDSPContext *c, enum AVSampleFormat fmt,
 
     if (ARCH_ARM)
         ff_flacdsp_init_arm(c, fmt, bps);
-    if (ARCH_X86)
+    if (ARCH_X86 && CONFIG_FLAC_DECODER)
         ff_flacdsp_init_x86(c, fmt, bps);
 }