screen: fix rare build failure on T_N undeclared

/usr/lfs/v0/rc-buildroot-test/scripts/instance-2/output/host/bin/arm-none-linux-gnueabi-gcc -c -I. -I.  -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -DETCSCREENRC='"/usr/etc/screenrc"' -DSCREENENCODINGS='"/usr/share/screen/utf8encodings"' -DHAVE_CONFIG_H -DGIT_REV=\"\" \
     -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64  -Os  -D_GNU_SOURCE list_display.c
In file included from screen.h:150:0,
                 from list_display.c:36:
display.h:154:19: error: 'T_N' undeclared here (not in a function)
   union tcu d_tcs[T_N];  /* terminal capabilities */

Macro T_N is defined in header file term.h but it may not be created
then fails. Backport patch to make sure term.h is created before compile
other source codes.

Fixes:
 - http://autobuild.buildroot.org/results/a62bea1fd32246526d59f029df3dca60f1cd710f



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>