Add stdplus dependency for pldm

pldm flight recorder feature in pldm uses stdplus::signal::block
API to block the SIGUSR1 linux signal.

Explicitly not adding this as dependency would ideally break the
compilation of pldm using subprojects.

Tested By:
1. compile pldm on ubuntu with out any openbmc - packages
2. the compilation breaks with undefined reference error
3. Put this patch in - and then recompile the code
4. now pldm compiles with out any errors.

Signed-off-by: Manojkiran Eda <manojkiran.eda@gmail.com>
Change-Id: I111f3581b898c71a5e4eeee24a0bfc89c4487021
diff --git a/libpldmresponder/meson.build b/libpldmresponder/meson.build
index 7d4ae6e..9ea74a3 100644
--- a/libpldmresponder/meson.build
+++ b/libpldmresponder/meson.build
@@ -1,4 +1,4 @@
-deps = [
+libpldmresponder_deps = [
   phosphor_dbus_interfaces,
   nlohmann_json,
   sdbusplus,
@@ -49,7 +49,7 @@
   'pldmresponder',
   sources,
   version: meson.project_version(),
-  dependencies: deps,
+  dependencies: libpldmresponder_deps,
   install: true)
 
 libpldmresponder = declare_dependency(
diff --git a/meson.build b/meson.build
index d86b450..4240916 100644
--- a/meson.build
+++ b/meson.build
@@ -71,6 +71,7 @@
   phosphor_dbus_interfaces = dependency('phosphor-dbus-interfaces')
   sdbusplus = dependency('sdbusplus')
   sdeventplus = dependency('sdeventplus')
+  stdplus = dependency('stdplus')
 
   if cpp.has_header('nlohmann/json.hpp')
     nlohmann_json = declare_dependency()
@@ -162,6 +163,7 @@
   libpldmutils,
   nlohmann_json,
   sdbusplus,
+  stdplus,
   sdeventplus,
   phosphor_dbus_interfaces,
 ]
diff --git a/subprojects/stdplus.wrap b/subprojects/stdplus.wrap
new file mode 100644
index 0000000..765ba71
--- /dev/null
+++ b/subprojects/stdplus.wrap
@@ -0,0 +1,6 @@
+[wrap-git]
+url = https://github.com/openbmc/stdplus
+revision = HEAD
+
+[provide]
+stdplus = stdplus_dep