build-sys: First pass at a meson-ified build system

This is a working implementation of a build with meson. The server,
utils, and most modules build with this, and it is possible to run from
a build tree and play/capture audio on ALSA devices.

There are a number of FIXMEs, of course, and a number of features that
need to be enabled (modules, dependencies, installation, etc.), but this
should provide everything we need to get there relatively quickly.

To use this, install meson (distro package, or mesonbuild.com) and run:

  $ cd <pulseaudio src dir>
  $ meson <builddir>
  $ ninja -C <builddir>

src/daemon/main.c

@@ -98,6 +98,15 @@
 #include "ltdl-bind-now.h"
 #include "server-lookup.h"
 
+#ifdef DISABLE_LIBTOOL_PRELOAD
+/* FIXME: work around a libtool bug by making sure we have 2 elements. Bug has
+ * been reported: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=29576 */
+const lt_dlsymlist lt_preloaded_symbols[] = {
+    { "@PROGRAM@", NULL },
+    { NULL, NULL }
+};
+#endif
+
 #ifdef HAVE_LIBWRAP
 /* Only one instance of these variables */
 int allow_severity = LOG_INFO;