[chore] Resolve more "warning C4127: conditional expression is constant" while building under MSVC (#3595)

NOISY warning on NINJA MSVC build log.
Complement for PR 3567. Now in another place.

D:\dev\eden\src\dynarmic\src\dynarmic\backend\x64\emit_x64_vector_floating_point.cpp(207): warning C4127: conditional expression is constant
D:\dev\eden\src\dynarmic\src\dynarmic\backend\x64\emit_x64_vector_floating_point.cpp(207): note: consider using 'if constexpr' statement instead

Signed-off-by: xbzk <xbzk@eden-emu.dev>

Co-authored-by: DraVee <dravee@eden-emu.dev>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3595
Reviewed-by: Lizzie <lizzie@eden-emu.dev>
Reviewed-by: DraVee <dravee@eden-emu.dev>
Co-authored-by: xbzk <xbzk@eden-emu.dev>
Co-committed-by: xbzk <xbzk@eden-emu.dev>

src/dynarmic/src/dynarmic/common/assert.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 // SPDX-FileCopyrightText: 2013 Dolphin Emulator Project
 // SPDX-FileCopyrightText: 2014 Citra Emulator Project
@@ -9,7 +9,7 @@
 // TODO: Use source_info?
 [[noreturn]] void assert_terminate_impl(const char* s);
 #ifndef ASSERT
-#   define ASSERT(expr) do if(!(expr)) [[unlikely]] assert_terminate_impl(__FILE__ ": " #expr); while(0)
+#   define ASSERT(expr) do { auto&& condition = !(expr); if(condition) [[unlikely]] assert_terminate_impl(__FILE__ ": " #expr); } while(0)
 #endif
 #ifndef UNREACHABLE
 #   ifdef _MSC_VER