Move the AVX2 (__m256d+FMA) and AArch64 NEON FFT intrinsics, plus the three
internal seam headers (wc_falcon_{fpr,fft,poly}.h), into falcon.c so the native
implementation is one translation unit -- matching how sha256.c and chacha.c
carry their SIMD backends inline (only hand-written .S stays a separate file).
The blocks are gated by WOLFSSL_FALCON_FFT_AVX2 / _NEON and need no per-file
CFLAGS: AVX2 self-annotates every function with target("avx2,fma") and NEON is
AArch64-baseline. Per-backend FPC_* macros are undef'd before redefinition, as
sha512.c does for SHA_METHOD. Only the generated fpr x86-64 asm remains a file.
Daniele Lacamera
502ebf4a5d