build: meson support for unit tests

Add support for building and running existing unit tests
under meson.

Fix a few test case failures that might surface from running
as non-root or without a full OpenBMC set of applications.

Fixes: openbmc/phosphor-logging#11

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I588c0b7d8dcdc60b9a03fee0b5d373d0023b0530
diff --git a/subprojects/googletest.wrap b/subprojects/googletest.wrap
new file mode 100644
index 0000000..56da9ef
--- /dev/null
+++ b/subprojects/googletest.wrap
@@ -0,0 +1,3 @@
+[wrap-git]
+url = https://github.com/google/googletest
+revision = HEAD