[gnome-system-monitor] Fix memory leaks when converting gchar* to string.

[Benoît Dejean <bdejean src gnome org>]

commit 0ec44c66f46ed2f06105d63d45ee129f914499d1
Author: Benoît Dejean <bdejean gmail com>
Date:   Thu Jun 15 07:48:00 2017 +0200

    Fix memory leaks when converting gchar* to string.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=783447

 src/proctable.cpp |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/proctable.cpp b/src/proctable.cpp
index 9525587..cbb0d85 100644
--- a/src/proctable.cpp
+++ b/src/proctable.cpp
@@ -927,9 +927,9 @@ ProcInfo::ProcInfo(pid_t pid)
     if (tooltip.empty())
         tooltip = procstate.cmd;
 
-    info->tooltip = g_markup_escape_text(tooltip.c_str(), -1);
+    info->tooltip = make_string(g_markup_escape_text(tooltip.c_str(), -1));
 
-    info->arguments = g_strescape(tooltip.c_str(), "\\\"");
+    info->arguments = make_string(g_strescape(tooltip.c_str(), "\\\""));
     g_strfreev(arguments);
 
     guint64 cpu_time = proctime.rtime;