[PATCH] UefiCpuPkg DxeRegisterCpuFeaturesLib: Fix VS2012 build failure

["Zeng, Star" <star.zeng@intel.com>]

The new VS2012 build failure is caused by 7a0df26.

xxx\registercpufeatureslib\dxeregistercpufeatureslib.c(258) :
 warning C4701: potentially uninitialized local variable 'MpEvent' used

It is a false positive alarm.
MpEvent is assigned at line 238 and will be used at line 258, both
lines are controlled by "if (CpuFeaturesData->NumberOfCpus > 1)".

This patch initializes MpEvent to suppress incorrect compiler/analyzer
warnings.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Dandan Bi <dandan.bi@intel.com>
Signed-off-by: Star Zeng <star.zeng@intel.com>
---
 .../RegisterCpuFeaturesLib/DxeRegisterCpuFeaturesLib.c      | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/DxeRegisterCpuFeaturesLib.c b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/DxeRegisterCpuFeaturesLib.c
index ffd99046a6cd..f87b2892aaae 100644
--- a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/DxeRegisterCpuFeaturesLib.c
+++ b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/DxeRegisterCpuFeaturesLib.c
@@ -229,6 +229,12 @@ CpuFeaturesInitialize (
   OldBspNumber = GetProcessorIndex (CpuFeaturesData);
   CpuFeaturesData->BspNumber = OldBspNumber;
 
+  //
+  //
+  // Initialize MpEvent to suppress incorrect compiler/analyzer warnings.
+  //
+  MpEvent = NULL;
+
   if (CpuFeaturesData->NumberOfCpus > 1) {
     Status = gBS->CreateEvent (
                     EVT_NOTIFY_WAIT,
-- 
2.21.0.windows.1