x86/vmx: replace unqualified ud2 instructions with BUG frames

x86/vmx: replace unqualified ud2 instructions with BUG frames

Using new _ASM_BUGFRAME* internals.

A side effect of complicating the ASM statements is that GCC now chooses to
out-of-line the stub functions, resulting in identical copies being present in
all translation units.  As with the stac()/clac() stubs, force them always
inline.

No functional change, other than the failure cases, which now produce a
far more clear error message.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>