win64: Correctly read the fifth parameter from the stack if we've pushed xmm registers

This fixes the umac test on win64.

ChangeLog

@@ -7,7 +7,9 @@
 	within this subfunction.
 	* x86_64/machine.m4 (W64_ENTRY): Use movdqu instead of movdqa for
 	saving xmm registers, since the stack is not guaranteed to be
-	16-byte aligned on win64.
+	16-byte aligned on win64. Take pushed xmm registers into account
+	when reading the fifth parameter from the stack.
+
 	* Makefile.in: Consistently use EXEEXT_FOR_BUILD.
 
 2013-04-21  Niels Möller  <nisse@lysator.liu.se>

x86_64/machine.m4

@@ -67,7 +67,7 @@ define(<XREG>,<ifelse(
 dnl W64_ENTRY(nargs, xmm_used)
 define(<W64_ENTRY>, <
   changequote([,])dnl
-  ifelse(<<<<<<<<<<<<<<< ignored; only for balancing)
+  ifelse(<<<<<<<<<<<<<<<< ignored; only for balancing)
   ifelse(W64_ABI,yes,[
     ifelse(eval($2 > 6), 1, [
       sub	[$]eval(8 + 16*($2 - 6)), %rsp
@@ -115,7 +115,11 @@ define(<W64_ENTRY>, <
       mov	%r9, %rcx
     ])
     ifelse(eval($1 >= 5), 1, [
-      mov	56(%rsp), %r8
+      ifelse(eval($2 > 6), 1, [
+        mov	eval(8 + 16*($2 - 6) + 56)(%rsp), %r8
+      ], [
+        mov	56(%rsp), %r8
+      ])
     ])
   ])
   changequote(<,>)dnl