scripts: add possibility to not override default connection timeout

Allow '-1' to be specified as CONNECTION_TIMEOUT to disable the use
of the connection timeout for wget.

Signed-off-by: Cody P Schafer <dev@codyps.com>
Message-Id: <cb33f8c2cbaf802d4f04.1399687632@localhost>
Patchwork-Id: 347582

 #!/bin/sh

 # Needed for systems without gettext

 $* -xc -o /dev/null - > /dev/null 2>&1 << EOF

 #include <libintl.h>

 int main()

 {

 	gettext("");

 	return 0;

 }

 EOF

 if [ ! "$?" -eq "0"  ]; then

 	echo -DKBUILD_NO_NLS;

 fi