package/postgis: disable protobuf support

package/postgis: disable protobuf support

- needs protobuf-c (not protobuf)
- protobuf-c configure tests are not cross-compile capable, even with

  ifeq ($(BR2_PACKAGE_PROTOBUF_C),y)
  POSTGIS_DEPENDENCIES += protobuf-c
  POSTGIS_CONF_OPTS += --with-protobuf
  POSTGIS_CONF_ENV += \
  	ac_cv_lib_protobuf_c_protobuf_c_message_init=yes \
  	ac_cv_lib_protobuf_c_protobuf_c_version=yes
  else
  POSTGIS_CONF_OPTS += --without-protobuf
  endif

  configure aborts with:

  checking for PROTOBUFC... yes
  checking protobuf-c/protobuf-c.h usability... yes
  checking protobuf-c/protobuf-c.h presence... yes
  checking for protobuf-c/protobuf-c.h... yes
  checking for protobuf_c_message_init in -lprotobuf-c... (cached) yes
  checking for protobuf_c_version in -lprotobuf-c... (cached) yes
  checking protobuf-c version... configure: error: in `.../build/postgis-3.1.1':
  configure: error: cannot run test program while cross compiling

Fixes:

  - http://autobuild.buildroot.net/results/8b95086b5e0876d0a4e41330446e767e4abd3729

  checking for PROTOBUFC... no
  libprotobuf-c not found in pkg-config
  checking protobuf-c/protobuf-c.h usability... no
  checking protobuf-c/protobuf-c.h presence... no
  checking for protobuf-c/protobuf-c.h... no
  configure: error: unable to find protobuf-c/protobuf-c.h using CPPFLAGS. You can disable MVT and Geobuf support using --without-protobuf

Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Reviewed-by: Maxim Kochetkov <fido_max@inbox.ru>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>