Revert "package/pkg-autotools: force cross compiling"

This reverts commit 83e06196 which
raises the following build failure with thttpd or wipe:

configure: warning: cross_compiling=yes: invalid host type
loading site script /dev/null
creating cache ./config.cache
configure: error: can only configure for one host and one target at a time

Fixes:
 - http://autobuild.buildroot.org/results/e2156c3747b37d0ec2559a67f2f468ad42a20dbc
 - http://autobuild.buildroot.org/results/a356dd0cd1fb4c9a1b9d6a4cbad4ae2a34dbb562



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>