OvmfPkg/CsmSupportLib: list "LegacyRegion.h" in the INF file
OvmfPkg/CsmSupportLib: list "LegacyRegion.h" in the INF file

Among other things, the header file provides (extern) declarations for the
EFI_LEGACY_REGION2_PROTOCOL member functions that are defined in
"LegacyRegion.c". This way "mLegacyRegion2" can be initialized near the
top of "LegacyRegion.c", ahead of the member function definitions.

Cc: Ard Biesheuvel <66d3c5fdaeea7ff1f996ad04f2c45e08ab38e2f5@linaro.org>
Cc: Jordan Justen <a79006884ba9cf5f4f7fcbb92a15b208780d8c97@intel.com>
Suggested-by: Michael Kinney <fd20bc543a9f65bb633fac7d08a403c1f1c8eb6c@intel.com>
Ref: eceeacc5b443184c66bbe56b32167659412ebeee@ORSMSX113.amr.corp.intel.com
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <7437296077edea1cb64451c122c4dac071f0cfbc@redhat.com>
Reviewed-by: Ard Biesheuvel <66d3c5fdaeea7ff1f996ad04f2c45e08ab38e2f5@linaro.org>
Reviewed-by: Jordan Justen <a79006884ba9cf5f4f7fcbb92a15b208780d8c97@intel.com>

MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2,MattDevo/edk2