UefiCpuPkg: LocalApicLib: Add API to set SoftwareEnable bit

The LocalApicLib does not provide a function to manage the state of the
Local APIC SoftwareEnable bit in the Spurious Vector register.  There
are cases where this bit needs to be managed without side effects to.
other Local APIC registers.  One use case is in the DebugAgent in the
SourceLevelDebugPkg.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Michael Kinney <michael.d.kinney@intel.com>
Reviewed-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18711 6f19259b-4bc3-4df7-8a09-765794883524

UefiCpuPkg/Include/Library/LocalApicLib.h

@@ -4,7 +4,7 @@
   Local APIC library assumes local APIC is enabled. It does not
   handles cases where local APIC is disabled.
 
-  Copyright (c) 2010 - 2014, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2010 - 2015, Intel Corporation. All rights reserved.<BR>
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
   which accompanies this distribution.  The full text of the license may be found at
@@ -227,6 +227,20 @@ SendInitSipiSipiAllExcludingSelf (
   IN UINT32          StartupRoutine
   );
 
+/**
+  Initialize the state of the SoftwareEnable bit in the Local APIC
+  Spurious Interrupt Vector register.
+
+  @param  Enable  If TRUE, then set SoftwareEnable to 1
+                  If FALSE, then set SoftwareEnable to 0.
+
+**/
+VOID
+EFIAPI
+InitializeLocalApicSoftwareEnable (
+  IN BOOLEAN  Enable
+  );
+
 /**
   Programming Virtual Wire Mode.