unittests: Adds support for 256-bit vpclmulqdq

It's easy because the test was already written for this in mind.

unittests/ASM/VEX/vpclmulqdq_256.asm

@@ -0,0 +1,50 @@
+%ifdef CONFIG
+{
+  "HostFeatures": ["AVX"],
+  "RegData": {
+      "XMM1": ["0xA76C4F06A12BFCE0", "0x9B80767F1E6A060F", "0xFFFFFFFFFFFFFFFF", "0xEEEEEEEEEEEEEEEE"],
+      "XMM2": ["0x6868C3F3AAED56E0", "0xF0FCE9E294E6E6DE", "0xDDDDDDDDDDDDDDDD", "0xCCCCCCCCCCCCCCCC"],
+      "XMM3": ["0x1E2017C5BEE29400", "0x38358E40CC367C7A", "0x4b4b4b4b4b4b4b4b", "0x4b4b4b4b4b4b4b4b"],
+      "XMM4": ["0xE208147952DE57A0", "0x317D360F86C80DC9", "0x4646464646464646", "0x4646464646464646"],
+      "XMM5": ["0xBBA54C87DA872B40", "0x6495428B7641EBE6", "0x4444444444444444", "0x4444444444444444"],
+      "XMM6": ["0x170B5A1B5CDD42EA", "0x719F094BB2358CA1", "0x4848484848484848", "0x4848484848484848"]
+  }
+}
+%endif
+
+lea rdx, [rel .data]
+
+; Load inputs
+vmovaps ymm1, [rdx + 32 * 0]
+vmovaps ymm2, [rdx + 32 * 1]
+
+; Fill result vectors with junk (ensure proper lane clearing is performed)
+vmovaps ymm3, [rdx + 32 * 0]
+vmovaps ymm4, [rdx + 32 * 0]
+vmovaps ymm5, [rdx + 32 * 0]
+vmovaps ymm6, [rdx + 32 * 0]
+
+; With imm = 0b00000000
+vpclmulqdq ymm3, ymm1, ymm2, 0
+
+; With imm = 0b00000001
+vpclmulqdq ymm4, ymm1, ymm2, 1
+
+; With imm = 0b00010000
+vpclmulqdq ymm5, ymm1, ymm2, 16
+
+; With imm = 0b00010001
+vpclmulqdq ymm6, ymm1, ymm2, 17
+
+hlt
+
+align 32
+.data:
+dq 0xA76C4F06A12BFCE0
+dq 0x9B80767F1E6A060F
+dq 0xFFFFFFFFFFFFFFFF
+dq 0xEEEEEEEEEEEEEEEE
+dq 0x6868C3F3AAED56E0
+dq 0xF0FCE9E294E6E6DE
+dq 0xDDDDDDDDDDDDDDDD
+dq 0xCCCCCCCCCCCCCCCC