Opus 1.5.x and main compilation failing with GCC 8.5.0

Opus 1.5.2 Buils is failing with gcc (GCC) 8.5.0 20210514 (Red Hat 8.5.0-18).

g++ 8.5.0 not compatible with AVX2 interensic.

../silk/x86/NSQ_del_dec_avx2.c: In function 'silk_nsq_del_dec_scale_states_avx2':
../silk/x86/NSQ_del_dec_avx2.c:959:43: warning: implicit declaration of function '_mm_loadu_si64'; did you mean '_mm_loadu_si32'? [-Wimplicit-function-declaration]
__m256i x = _mm256_cvtepi16_epi64(_mm_loadu_si64(&x16[i]));
^~~~~~~~~~~~~~
_mm_loadu_si32
../silk/x86/NSQ_del_dec_avx2.c:959:43: warning: nested extern declaration of '_mm_loadu_si64' [-Wnested-externs]
../silk/x86/NSQ_del_dec_avx2.c:959:43: error: incompatible type for argument 1 of '_mm256_cvtepi16_epi64'
__m256i x = _mm256_cvtepi16_epi64(_mm_loadu_si64(&x16[i]));
^~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/lib/gcc/x86_64-redhat-linux/8/include/immintrin.h:43,
from ../silk/x86/NSQ_del_dec_avx2.c:37:
/usr/lib/gcc/x86_64-redhat-linux/8/include/avx2intrin.h:468:32: note: expected '__m128i' {aka '__vector(2) long long int'} but argument is of type 'int'
_mm256_cvtepi16_epi64 (__m128i __X)

Reproduce the Opus 1.5.2 build with GCC 8.5.0, then inspect silk/x86/NSQ_del_dec_avx2.c around line 959 and the AVX2 intrinsic headers involved. Confirm the build succeeds with GCC 8.5.0 without the reported _mm_loadu_si64 type error.