Resolve Meson issues

This commit includes fixes in the repo:

1. Moving experimental filesystem to filesystem
2. Errors that meson identified

Signed-off-by: Ratan Gupta <ratankgupta31@gmail.com>
Change-Id: I93c77c2a434275c4da3ca4549919eaa55b57f481
diff --git a/test/test_snmp_client.cpp b/test/test_snmp_client.cpp
index 1dd9eb4..698c491 100644
--- a/test/test_snmp_client.cpp
+++ b/test/test_snmp_client.cpp
@@ -22,12 +22,11 @@
   public:
     sdbusplus::bus::bus bus;
     ConfManager manager;
-    std::string confDir;
     TestSNMPClient() :
         bus(sdbusplus::bus::new_default()), manager(bus, mgrObjPath)
     {
         char tmp[] = "/tmp/snmpClient.XXXXXX";
-        std::string confDir = mkdtemp(tmp);
+        auto confDir = mkdtemp(tmp);
         manager.dbusPersistentLocation = confDir;
     }
 
diff --git a/test/test_snmp_conf_manager.cpp b/test/test_snmp_conf_manager.cpp
index bcf89e7..de89272 100644
--- a/test/test_snmp_conf_manager.cpp
+++ b/test/test_snmp_conf_manager.cpp
@@ -21,12 +21,16 @@
   public:
     sdbusplus::bus::bus bus;
     ConfManager manager;
+    // confDir could have been created locally in the
+    // TestSNMPConfManager but somehow that is leading
+    // to segmentation fault while running the unit test.
+    // TODO: https://github.com/openbmc/phosphor-snmp/issues/5
     std::string confDir;
     TestSNMPConfManager() :
         bus(sdbusplus::bus::new_default()), manager(bus, managerObjPath)
     {
         char tmp[] = "/tmp/snmpManager.XXXXXX";
-        std::string confDir = mkdtemp(tmp);
+        confDir = mkdtemp(tmp);
         manager.dbusPersistentLocation = confDir;
     }
 
diff --git a/test/test_snmp_serialize.cpp b/test/test_snmp_serialize.cpp
index 1b0928e..627045b 100644
--- a/test/test_snmp_serialize.cpp
+++ b/test/test_snmp_serialize.cpp
@@ -4,7 +4,7 @@
 
 #include <netinet/in.h>
 
-#include <experimental/filesystem>
+#include <filesystem>
 #include <fstream>
 
 #include <gtest/gtest.h>
@@ -17,7 +17,7 @@
 {
 
 constexpr auto clientObjPath = "/xyz/openbmc_test/snmp/client";
-namespace fs = std::experimental::filesystem;
+namespace fs = std::filesystem;
 
 class TestSerialize : public testing::Test
 {