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 gcc-4.4.0.orig/boehm-gc/include/gc.h gcc-4.4.0/boehm-gc/include/gc.h

 --- gcc-4.4.0.orig/boehm-gc/include/gc.h	2007-04-23 23:10:09.000000000 +0200

 +++ gcc-4.4.0/boehm-gc/include/gc.h	2009-05-27 21:38:55.000000000 +0200

 @@ -503,7 +503,7 @@

  #if defined(__linux__) || defined(__GLIBC__)

  # include <features.h>

  # if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 1 || __GLIBC__ > 2) \

 -     && !defined(__ia64__)

 +     && !defined(__ia64__) && !defined(__UCLIBC__)

  #   ifndef GC_HAVE_BUILTIN_BACKTRACE

  #     define GC_HAVE_BUILTIN_BACKTRACE

  #   endif