lls.asm: put avx code under if HAVE_AVX_EXTERNAL

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavutil/x86/lls.asm

@@ -125,6 +125,7 @@ cglobal update_lls, 2,5,8, ctx, var, i, j, covar2
 .ret:
     REP_RET
 
+%if HAVE_AVX_EXTERNAL
 INIT_YMM avx
 cglobal update_lls, 3,6,8, ctx, var, count, i, j, count2
     %define covarq ctxq
@@ -194,3 +195,4 @@ cglobal update_lls, 3,6,8, ctx, var, count, i, j, count2
     jle .loop2x1
 .ret:
     REP_RET
+%endif