MdePkg: restrict UefiMultiPhase.h contents if VFRCOMPILE defined
MdePkg: restrict UefiMultiPhase.h contents if VFRCOMPILE defined

Turns out all .vfr files in the tree interacting with DynamicPcds
manually copy the same set of EFI_VARIABLE_* definitions, since the rest
of UefiMultiPhase.h is incompatible with VfrCompile.

For now, reshuffle these definitions to the start of the file, and put
the rest of the file behind #ifndef VFRCOMPILE to permit direct
inclusion in .vfr source files.

https://bugzilla.tianocore.org/show_bug.cgi?id=878 has been raised to
request VfrCompile is extended to support the original format.

Cc: Michael D Kinney <fd20bc543a9f65bb633fac7d08a403c1f1c8eb6c@intel.com>
Cc: Liming Gao <6480311aeeb4b006862f6d13ebabddc03f51e507@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Leif Lindholm <a613079f0455438b29e28a9c5b9eb3779a81a33a@linaro.org>
Reviewed-by: Star Zeng <5c6bb72efe464613af94e84c05522a361b23844a@intel.com>
Reviewed-by: Liming Gao <6480311aeeb4b006862f6d13ebabddc03f51e507@intel.com>

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