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/Makefile.in ltrace-0.5.3/Makefile.in

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

 +++ ltrace-0.5.3/Makefile.in	2011-08-21 18:40:53.000000000 +0200

 @@ -39,7 +40,7 @@

  		$(CC) $(LDFLAGS) $^ $(LIBS) -o $@

  libltrace.a: 	sysdeps/sysdep.o $(OBJ)

 -		$(AR) rcv $@ $^

 +		$(AR) rscv $@ $^

  $(OBJ):		sysdeps/sysdep.o