x86/hvm: address violations of MISRA C Rule 20.7

MISRA C Rule 20.7 states: "Expressions resulting from the expansion
of macro parameters shall be enclosed in parentheses". Therefore, some
macro definitions should gain additional parentheses to ensure that all
current and future users will be safe with respect to expansions that
can possibly alter the semantics of the passed-in macro parameter.

No functional change.

Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/hvm/domain.c

@@ -132,9 +132,9 @@ int arch_set_info_hvm_guest(struct vcpu *v, const struct vcpu_hvm_context *ctx)
     s = (struct segment_register)                                           \
         { 0, { (r)->s ## _ar }, (r)->s ## _limit, (r)->s ## _base };        \
     /* Set accessed / busy bit for present segments. */                     \
-    if ( s.p )                                                              \
-        s.type |= (x86_seg_##s != x86_seg_tr ? 1 : 2);                      \
-    check_segment(&s, x86_seg_ ## s); })
+    if ( (s).p )                                                            \
+        (s).type |= (x86_seg_ ## s != x86_seg_tr ? 1 : 2);                  \
+    check_segment(&(s), x86_seg_ ## s); })
 
         rc = SEG(cs, regs);
         rc |= SEG(ds, regs);