subprojects: Add phosphor-objmgr wrap

The nvme test suite requires the mapper. Include a wrap for
phosphor-objmgr such that we can build the mapperx binary if one is not
present in the system environment.

Change-Id: I60f4cfe62452f9111090959f5858cfe873b09f65
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>

subprojects/phosphor-objmgr.wrap

diff --git a/subprojects/phosphor-objmgr.wrap b/subprojects/phosphor-objmgr.wrap
new file mode 100644
index 0000000..61c2e28
--- /dev/null
+++ b/subprojects/phosphor-objmgr.wrap
@@ -0,0 +1,6 @@
+[wrap-git]
+url = https://github.com/openbmc/phosphor-objmgr.git
+revision = HEAD
+
+[provide]
+phosphor-objmgr = mapper_dep