Land Sysprof 2.x

This is a major redesign a modernization of Sysprof. The core data
structures and design are largely the same, but it has been ported to
Gtk3 and has lots of additions that should make your profiling experience
smoother. Especially for those that are new to profiling.

There are some very simple help docs added, but we really need the
experts to come in and write some documentation here.

m4/glibc2.m4

@@ -0,0 +1,31 @@
+# glibc2.m4 serial 3
+dnl Copyright (C) 2000-2002, 2004, 2008, 2010-2015 Free Software Foundation,
+dnl Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+# Test for the GNU C Library, version 2.0 or newer.
+# From Bruno Haible.
+
+AC_DEFUN([gt_GLIBC2],
+  [
+    AC_CACHE_CHECK([whether we are using the GNU C Library 2 or newer],
+      [ac_cv_gnu_library_2],
+      [AC_EGREP_CPP([Lucky GNU user],
+        [
+#include <features.h>
+#ifdef __GNU_LIBRARY__
+ #if (__GLIBC__ >= 2) && !defined __UCLIBC__
+  Lucky GNU user
+ #endif
+#endif
+        ],
+        [ac_cv_gnu_library_2=yes],
+        [ac_cv_gnu_library_2=no])
+      ]
+    )
+    AC_SUBST([GLIBC2])
+    GLIBC2="$ac_cv_gnu_library_2"
+  ]
+)