wolfcrypt/src/port/af_alg/afalg_aes.c: check for null key arg;
configure.ac: rename BUILD_FIPS_CURRENT to BUILD_FIPS_V2_PLUS (no functional change), and remove unused ARMASM_DIST_SOURCES set up code added in #9332;
src/include.am:
* set up $(ARMASM_SHA256_C), and use it to properly include wolfcrypt/src/sha256.c alongside armasm when appropriate;
* fix gating on Curved25519 armasm (BUILD_FIPS_V6_PLUS, not BUILD_FIPS_V6);
tests/api/test_aes.c and wolfcrypt/test/test.c: gate out incompatible coverage for WOLFSSL_AFALG and WOLFSSL_KCAPI (test_wc_AesCbcEncryptDecrypt_MultiBlocks(), test_wc_AesCtrSetKey*(), test_wc_AesCtrEncrypt*(), test_wc_AesGcmEncryptDecrypt_Sizes()).