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 -dur strace-4.5.15.orig/system.c strace-4.5.15/system.c

 --- strace-4.5.15.orig/system.c	2007-01-17 00:22:36.000000000 +0100

 +++ strace-4.5.15/system.c	2007-07-14 19:28:41.000000000 +0200

 @@ -1612,7 +1612,9 @@

  	{ CTL_KERN, "CTL_KERN" },

  	{ CTL_VM, "CTL_VM" },

  	{ CTL_NET, "CTL_NET" },

 +#ifdef CTL_PROC

  	{ CTL_PROC, "CTL_PROC" },

 +#endif

  	{ CTL_FS, "CTL_FS" },

  	{ CTL_DEBUG, "CTL_DEBUG" },

  	{ CTL_DEV, "CTL_DEV" },