x86/hvm: Reduce stack usage from HVMTRACE_ND()

x86/hvm: Reduce stack usage from HVMTRACE_ND()

It is pointless to write all 6 entries and only consume the useful subset.
bloat-o-meter shows quite how obscene the overhead is in vmx_vmexit_handler(),
weighing in at 12% of the function arranging unread zeroes on the stack, and
8% for svm_vmexit_handler().

  add/remove: 0/0 grow/shrink: 0/20 up/down: 0/-1929 (-1929)
  Function                                     old     new   delta
  hvm_msr_write_intercept                     1049    1033     -16
  vmx_enable_intr_window                       238     214     -24
  svm_enable_intr_window                       337     313     -24
  hvmemul_write_xcr                            115      91     -24
  hvmemul_write_cr                             350     326     -24
  hvmemul_read_xcr                             115      91     -24
  hvmemul_read_cr                              146     122     -24
  hvm_mov_to_cr                                438     414     -24
  hvm_mov_from_cr                              253     229     -24
  vmx_intr_assist                             1150    1118     -32
  svm_intr_assist                              459     427     -32
  hvm_rdtsc_intercept                          138     106     -32
  hvm_msr_read_intercept                       898     866     -32
  vmx_vmenter_helper                          1142    1094     -48
  vmx_inject_event                             813     765     -48
  svm_vmenter_helper                           238     187     -51
  hvm_hlt                                      197     146     -51
  svm_inject_event                            1678    1614     -64
  svm_vmexit_handler                          5880    5392    -488
  vmx_vmexit_handler                          7281    6438    -843
  Total: Before=3644277, After=3642348, chg -0.05%

Adjust all users of HVMTRACE_ND(), using TRC_PAR_LONG() where appropriate
instead of opencoding it.

The 0 case needs a little help.  All object in C must have a unique address
and _d is passed by pointer.  Explicitly permit the optimiser to drop the
array.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>