Enable the ARM64 target on the ARM64EC ABI.

ARM64EC enables both _M_AMD64 and _M_ARM64EC. We already exclude ARM64EC
from the SSE2 detection, but it was missing for the X64 target
detection.

However we're now fine to enable the ARM64 target. At least my kernels
compile fine (as good as on the raw arm64) on MSVC.

Related: https://techcommunity.microsoft.com/blog/windowsosplatform/getting-to-know-arm64ec-defines-and-intrinsic-functions/2957235

Author: degasus

include/xsimd/config/xsimd_config.hpp

@@ -51,7 +51,7 @@
  *
  * Set to 1 if the target is the x86 architecture family.
  */
-#if defined(__x86_64__) || defined(__i386__) || defined(_M_AMD64) || defined(_M_IX86)
+#if (defined(__x86_64__) || defined(__i386__) || defined(_M_AMD64) || defined(_M_IX86)) && !defined(_M_ARM64EC)
 #define XSIMD_TARGET_X86 1
 #else
 #define XSIMD_TARGET_X86 0
@@ -422,7 +422,7 @@
  *
  * Set to 1 if the target is in the ARM architecture family in 64 bits, to 0 otherwise
  */
-#if defined(__aarch64__) || defined(_M_ARM64)
+#if defined(__aarch64__) || defined(_M_ARM64) || defined(_M_ARM64EC)
 #define XSIMD_TARGET_ARM64 1
 #else
 #define XSIMD_TARGET_ARM64 0