tools: Add pd, a test tool for libpldm

As per the comment in the implementation:

> `grep 'p.*l.*d.*m' /usr/share/dict/words` found 'palladium', which has
> element symbol Pd.

Change-Id: Idbfb15e3382cccb0fde48dc2d5ee8de14fc30816
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
diff --git a/tools/meson.build b/tools/meson.build
new file mode 100644
index 0000000..d047267
--- /dev/null
+++ b/tools/meson.build
@@ -0,0 +1,3 @@
+if get_option('abi').contains('testing')
+    executable('pd', 'pd.c', dependencies: [libpldm_dep])
+endif