[CM] local variables not shadowing in defprocess

[Anders Vinjar]

I beleive theres some bug somewhere in latest (CVS cm-2.5.0).
Local variables set inside #'defprocess are not looked up if
theres a global variable with the same name.

Heres an example:

CM> *cm-date*
; Evaluation aborted
CM> (cm-version)
"Common Music 2.5.0"
CM> (setf localvar 200)
200
CM> (defprocess tester ()
       (let ((localvar 100))
         (process repeat 4
                  do
                  (pprint localvar))))
TESTER
CM> (events (tester) "test.midi")

200
200
200
200
"test.midi"
CM>