Revert "x86: fft: win64: fix stack alignment for memcpy() call"

This reverts commit 8725da49.

Necerrary to revert 82992604.

libavcodec/x86/fft_mmx.asm

@@ -641,21 +641,19 @@ cglobal fft_permute, 2,7,1
 %if ARCH_X86_64
     mov     r0, r1
     mov     r1, r5
-%endif
-%if WIN64
-    sub     rsp, 8
-    call    memcpy
-    add     rsp, 8
-    RET
-%elif ARCH_X86_64
-    jmp     memcpy
 %else
     push    r2
     push    r5
     push    r1
+%endif
+%if ARCH_X86_64 && WIN64 == 0
+    jmp     memcpy
+%else
     call    memcpy
+%if ARCH_X86_32
     add     esp, 12
-    RET
+%endif
+    REP_RET
 %endif
 
 cglobal imdct_calc, 3,5,3