infra/pkg-autotools: cleanup the gettextize step

Align the way we call gettextize to the way we call autoreconf:
  - provide the $(GETTEXTIZE) variable
  - pass $(HOST_CONFIGURE_OPTS) in the environment
  - pass the fully-qualified path to autom4te
  - use of -f even if the package provides its own options

Some eye-candy in the output of gettextize.

Thanks to Gustavo for pointing out the discrepancy between the way we
call gettextize and the way we call autoreconf, and to Thomas for the
live debug session. ;-)

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Gustavo Zacarias <gustavo@zacarias.com.ar>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Thomas De Schampheleire <patrickdepinguin@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>