Include the full version number in the directory paths installed.
Change the version string so that it does not break 'make', and so that it has no '/' (it would be a hell if installed directories would mirror the SVN branches... :-/ )
Do not use implicit rules for the Makefile.
Simplify and enc=hance the --local test to refuse (un)installing.
Double-quotes variables, they are based on user input.
Eye-candy in the 'compile' and install messages.

/trunk/configure | 26 14 12 0 ++++++++++---------
/trunk/Makefile.in | 83 45 38 0 +++++++++++++++++++++++++++++++++---------------------------
2 files changed, 59 insertions(+), 50 deletions(-)

 diff -durN gcc-4.2.1.orig/boehm-gc/include/gc.h gcc-4.2.1/boehm-gc/include/gc.h

 --- gcc-4.2.1.orig/boehm-gc/include/gc.h	2006-09-18 20:45:08.000000000 +0200

 +++ gcc-4.2.1/boehm-gc/include/gc.h	2007-08-03 20:33:00.000000000 +0200

 @@ -502,7 +502,7 @@

  #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