Both the Makefile and the script that is used on OSX to create the binary
installer refer to the directory containing the Makefile using the name
'config'. This name was changed with the new ABI (with default build flags
it is now named config-3.2m).  This patch ensures that both files use the
correct name.

The build-installer.py script contains one other change: it now tests for the
Tcl/Tk framework version by looking at the 'Current' symlink in the framework
instead of runnning a script. This makes it possible to verify the version
that is in the SDK that's used during the build instead of the version that
is installed on the system.