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>

 From 83a09cd5c9ed9afd87a7d1d17319c2fd2203ad0f Mon Sep 17 00:00:00 2001

 From: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

 Date: Thu, 21 Jan 2010 10:36:13 +0100

 Subject: [PATCH 04/15] rpc: fix typo in version mismatch msg

 Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

 ---

  libc/inet/rpc/rpc_prot.c |    2 +-

  1 files changed, 1 insertions(+), 1 deletions(-)

 diff --git a/libc/inet/rpc/rpc_prot.c b/libc/inet/rpc/rpc_prot.c

 index 74658e6..229f988 100644

 --- a/libc/inet/rpc/rpc_prot.c

 +++ b/libc/inet/rpc/rpc_prot.c

 @@ -229,7 +229,7 @@ rejected (enum reject_stat rjct_stat,

  {

    switch (rjct_stat)

      {

 -    case RPC_VERSMISMATCH:

 +    case RPC_MISMATCH:

        error->re_status = RPC_VERSMISMATCH;

        return;

      case AUTH_ERROR:

 -- 

 1.6.6.1