[patch] Add host as valid build target to configure's help

[idefix]

According to ​HelperRules, host is also a valid build target. It is needed to build bfs_fuse on Linux.

Attached patch​ will add this target to the help of configure and also fix a paste error introduced in hrev49029.

[waddlesplash]

I think you want --host-only?

[idefix]

As you can see in the script attached to ticket:6014, both --host-only and --target=host are needed.

Only providing --host-only results in jam segfaulting due to a stack overflow:

jeroen@Gromit:~/Builds/Haiku/host-only/haiku$ ./configure --host-only
jeroen@Gromit:~/Builds/Haiku/host-only/haiku$ jam -q "<build>bfs_fuse"
Starting build of type regular ... 
AddHaikuImagePackages: package bash not available! 
AddHaikuImagePackages: package coreutils not available! 
AddHaikuImagePackages: package curl not available! 
AddHaikuImagePackages: package freetype not available! 
AddHaikuImagePackages: package icu not available! 
AddHaikuImagePackages: package libsolv not available! 
AddHaikuImagePackages: package zlib not available! 
AddHaikuImagePackages: package gcc_syslibs not available! 
/home/jeroen/Builds/Haiku/host-only/haiku/src/add-ons/kernel/bus_managers/config_manager/arch/Jamfile: No such file or directory
/home/jeroen/Builds/Haiku/host-only/haiku/src/add-ons/kernel/bus_managers/isa/arch/Jamfile: No such file or directory
/home/jeroen/Builds/Haiku/host-only/haiku/src/add-ons/kernel/bus_managers/pci/arch/Jamfile: No such file or directory
Segmentation fault (core dumped)
jeroen@Gromit:~/Builds/Haiku/host-only/haiku$ 

[waddlesplash]

Applied in hrev49919. Thanks!