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 -ru ltrace-0.5.3.org/configure ltrace-0.5.3/configure

 --- ltrace-0.5.3.org/configure	2011-08-21 18:55:15.000000000 +0200

 +++ ltrace-0.5.3/configure	2011-08-21 18:54:46.000000000 +0200

 @@ -15,8 +15,12 @@

  echo $PACKAGE_VERSION

  echo -n "checking HOST_OS... "

 -HOST_OS=$( uname -s )

 -if [ "$HOST_OS" = "Linux" ]

 +if [ -z "$HOST_OS" ] ; then

 +  HOST_OS=$( uname -s )

 +else

 +  echo -n "using preset: "

 +fi

 +if [ "$HOST_OS" = "Linux" -o "$HOST_OS" = "linux" ]

  then

    HOST_OS="linux-gnu"

  fi