meson: Make mpegts lib build when using subprojects

The headers passed as parametter are relative to the build dir
basically "../subproject/gst-plugins-bad/gst-libs/gst/mpegts/XXX.h"
but that does not match what is needed at build time when building as
subproject, also we always add current dir as include_dir so we are
safe including directly.

And link mpegtsdemux against the 'math' library as it is needed.

gst-libs/gst/mpegts/mpegts_enum.py

@@ -5,7 +5,7 @@
 # make special characters such as \n go through all
 # backends is a fool's errand.
 
-import sys, os, shutil, subprocess
+import sys, os, subprocess
 
 cmd = []
 argn = 1
@@ -20,7 +20,7 @@ for arg in sys.argv[1:]:
 ofilename = sys.argv[argn]
 headers = sys.argv[argn + 1:]
 
-inc = '\n'.join(['#include"%s"' % i for i in headers])
+inc = '\n'.join(['#include"%s"' % os.path.basename(i) for i in headers])
 
 h_array = ['--fhead',
            "#ifndef __GST_MPEGTS_ENUM_TYPES_H__\n#define __GST_MPEGTS_ENUM_TYPES_H__\n\n#include <glib-object.h>\n\nG_BEGIN_DECLS\n",

gst/mpegtsdemux/meson.build

@@ -12,7 +12,7 @@ gstmpegtsdemux = library('gstmpegtsdemux',
   c_args : gst_plugins_bad_args + ['-DGST_USE_UNSTABLE_API'],
   include_directories : [configinc, libsinc],
   dependencies : [gstcodecparsers_dep, gstmpegts_dep, gsttag_dep,
-		  gstpbutils_dep, gstaudio_dep, gstbase_dep],
+		  gstpbutils_dep, gstaudio_dep, gstbase_dep, mathlib],
   install : true,
   install_dir : plugins_install_dir,
 )

meson.build

@@ -305,6 +305,8 @@ if x11_dep.found()
   cdata.set('HAVE_X11', 1)
 endif
 
+mathlib = cc.find_library('m', required : false)
+
 if host_machine.system() == 'windows'
   winsock2 = [cc.find_library('ws2_32')]
 else