Disable tracing support for dtrace and systemtap in host build

The glib host build auto-detects whether tracing support for dtrace/systemtap should be enabled or not, when it finds for example dtrace it will enable tracing support  for dtrace and use the external dtrace during the build process. This causes trouble during the build since python things get messed up. 
This can be resolved by disabling tracing in glib during configuration.

````
Making all in glib
make[3]: Entering directory `/mnt/data/raspberrypi/OpenELEC/build.OpenELEC-Nox.arm-devel/glib-2.34.3/.x86_64-pc-linux-gnu/glib'
  GEN      glibconfig-stamp
  GEN      glib_probes.h
  GEN      glib_probes.o
Traceback (most recent call last):
  File "/usr/bin/dtrace", line 20, in <module>
    from subprocess import call
  File "/usr/lib/python2.7/subprocess.py", line 427, in <module>
    import select
ImportError: /usr/lib/python2.7/lib-dynload/select.so: undefined symbol: _PyInt_AsInt
Traceback (most recent call last):
  File "/usr/bin/dtrace", line 20, in <module>
    from subprocess import call
  File "/usr/lib/python2.7/subprocess.py", line 427, in <module>
    import select
ImportError: /usr/lib/python2.7/lib-dynload/select.so: undefined symbol: _PyInt_AsInt
make[3]: *** [glib_probes.o] Error 1
make[3]: *** Waiting for unfinished jobs....
make[3]: *** [glib_probes.h] Error 1
config.status: executing glib/glibconfig.h commands
config.status: glib/glibconfig.h is unchanged