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>

 diff -dur strace-4.5.16.orig/syscall.c strace-4.5.16/syscall.c

 --- strace-4.5.16.orig/syscall.c	2007-07-14 19:21:44.000000000 +0200

 +++ strace-4.5.16/syscall.c	2007-07-14 19:22:49.000000000 +0200

 @@ -125,6 +125,18 @@

  #define TP TRACE_PROCESS

  #define TS TRACE_SIGNAL

 +#ifndef HAVE_STATFS64

 +/*

 + * Ugly hacks for systems that do not have LFS

 + */

 +

 +#define sys_truncate64  sys_truncate

 +#define sys_ftruncate64 sys_ftruncate

 +#define sys_getdents64  sys_getdents

 +#define sys_statfs64    sys_statfs

 +#define sys_fstatfs64   sys_fstatfs

 +#endif

 +

  static const struct sysent sysent0[] = {

  #include "syscallent.h"

  };