config: add an option not to remove the destination directory

In certain circumstances, removing the destination/installation directory
is a bad idea. For example, when the build environment is already taking
care of sanitising the build tree, and pre-installs stuff in there, it is
a very bad idea to remove the destination directory.

This happens now in buildroot, as the crostool-NG backend now installs the
toolchain in the common host-tools directory, and pre-install there a few
host-utilities (eg. host-automake and host-gawk).

Provide a config knob to turn on/off the removal of the destination
directory, defaulting to 'y' (previous behavior), and forced to 'n' when
used as a backend.

Reported-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

# Overall toolchain configuration: paths, jobs, etc...

# Allow unconditional usage of tristates

config MODULES

    bool

    default y

menu "Paths and misc options"

source "config/global/ct-behave.in"

source "config/global/paths.in"

source "config/global/download.in"

source "config/global/extract.in"

source "config/global/build-behave.in"

source "config/global/logging.in"

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