Allow multi-word "install" command.

Autoconf can determine that the correct install command includes flags,
e.g., "/usr/bin/install -c". When using this as a command, we can't
enclose the value in double-quotes, as that makes some shells use the
whole expression as a filename:

# this is the value returned by autoconf and stored in CT_install
$ ins="/usr/bin/install -c"

# if we call it with quotes, the command is not found
$ "${ins}"
bash: /usr/bin/install -c: No such file or directory

# removing the quotes lets it work as expected
$ ${ins}
/usr/bin/install: missing file operand
Try `/usr/bin/install --help' for more information.

Signed-Off-By: Anthony Foiani <anthony.foiani@gmail.com>

 diff -durN ltrace-0.4.orig/configure ltrace-0.4/configure

 --- ltrace-0.4.orig/configure	2008-10-23 23:19:38.000000000 +0200

 +++ ltrace-0.4/configure	2008-10-23 23:19:06.000000000 +0200

 @@ -1392,6 +1392,9 @@

  HOST_OS="$host_os"

 +case "${HOST_OS}" in

 +  linux-*) HOST_OS=linux-gnu;;

 +esac

  ac_ext=c

 diff -durN ltrace-0.4.orig/configure.ac ltrace-0.4/configure.ac

 --- ltrace-0.4.orig/configure.ac	2008-10-23 23:19:43.000000000 +0200

 +++ ltrace-0.4/configure.ac	2008-10-23 23:18:44.000000000 +0200

 @@ -7,6 +7,9 @@

  dnl Check host system type

  AC_CANONICAL_HOST

  HOST_OS="$host_os"

 +case "${HOST_OS}" in

 +  linux-*) HOST_OS=linux-gnu;;

 +esac

  AC_SUBST(HOST_OS)

  dnl Checks for programs.