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>

 # Default test suite configuration

 # Default DejaGnu configuration

 DG_TOOLNAME = gcc

 DG_TARGET_HOSTNAME = 127.0.0.1

 DG_TARGET_USERNAME = root

 # Default tests

 DG_C_TESTS = 

 DG_CPP_TESTS =