x86: Fix compiler warning

arch/x86/crtools.c: In function ‘arch_alloc_thread_info’:
arch/x86/crtools.c:271:6: error: ‘with_xsave’ may be used uninitialized in this function [-Werror=uninitialized]

Actually the with_xsave is with_fpu dependant, but some gccs
can't guess that fact :\
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

arch/x86/crtools.c

@@ -228,7 +228,7 @@ err:
 int arch_alloc_thread_info(CoreEntry *core)
 {
 	size_t sz;
-	bool with_fpu, with_xsave;
+	bool with_fpu, with_xsave = false;
 	void *m;
 	ThreadInfoX86 *ti = NULL;