Fix naked_asm_corner_cases.d test for Windows x64 ABI

The multiPath function was using SysV ABI register (EDI) for the first
argument, but Windows x64 uses ECX. Add version(Windows) block to use
the correct register on each platform.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: Dev VM

tests/codegen/naked_asm_corner_cases.d

@@ -81,18 +81,33 @@ extern(C) int backwardJump() {
 // ASM: .LmultiPath_done:
 extern(C) int multiPath(int x) {
     asm { naked; }
-    version(D_InlineAsm_X86_64) asm {
-        // x is in EDI on SysV ABI
-        test EDI, EDI;
-        jz path1;
-        jmp path2;
-    path1:
-        mov EAX, 10;
-        jmp done;
-    path2:
-        mov EAX, 20;
-    done:
-        ret;
+    version(D_InlineAsm_X86_64) {
+        version(Windows) asm {
+            // x is in ECX on Windows x64 ABI
+            test ECX, ECX;
+            jz path1;
+            jmp path2;
+        path1:
+            mov EAX, 10;
+            jmp done;
+        path2:
+            mov EAX, 20;
+        done:
+            ret;
+        }
+        else asm {
+            // x is in EDI on SysV ABI
+            test EDI, EDI;
+            jz path1;
+            jmp path2;
+        path1:
+            mov EAX, 10;
+            jmp done;
+        path2:
+            mov EAX, 20;
+        done:
+            ret;
+        }
     }
 }