Add -mno-red-zone to CFLAGS for x86-64

This is required in order to use the stack in inline assembly (like
pushf; pop reg) without clashing with the compiler's stack assignment.

Fixes problems with GCC 4.5.1.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
svm: fix mode switch testcase

This was broken because it needed the 32-bit and 16-bit selectors.
Add them back to cstart64.S, and change svm.c to use symbolic names.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
vmx: actually test vmptrld, not vmclear

test_vmptrld was actually invoking vmclear.  make_vmcs_current is
the wrapper for vmptrld, not vmcs_clear!

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>