PEL: MRU callout SRC substructure

This substructure is part of the callout subsection in the SRC section
of a PEL, and contains information about Manufacturing Replaceable Units
(MRUs).  MRUs are components on a parent FRU (Field Replaceable Unit)
that may be able to be replaced in a manufacturing environment, hence
the name.

This substructure includes a list of <priority, MRU ID> pairs, where the
priority is the same priority value type as used elsewhere in the SRC
section ('H', 'M', 'L', etc), and the MRU ID is a 4B ID that development
will tell manufacturing the meanings of.

This commit only adds support for creating an object from a flattened PEL,
such as one that comes down from the host.  A future commit will handle
creating it from scratch for BMC errors.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I6352e1a3cb84db0516902786faca4c387afef411
diff --git a/extensions/openpower-pels/openpower-pels.mk b/extensions/openpower-pels/openpower-pels.mk
index 550530c..fdc998d 100644
--- a/extensions/openpower-pels/openpower-pels.mk
+++ b/extensions/openpower-pels/openpower-pels.mk
@@ -8,6 +8,7 @@
 	extensions/openpower-pels/generic.cpp \
 	extensions/openpower-pels/log_id.cpp \
 	extensions/openpower-pels/manager.cpp \
+	extensions/openpower-pels/mru.cpp \
 	extensions/openpower-pels/mtms.cpp \
 	extensions/openpower-pels/paths.cpp \
 	extensions/openpower-pels/pce_identity.cpp \