#214 unused variable listPtr

[Jan Nijtmans]

When compiling Itcl 3.4.1 with gcc-4..6 as-is:
./generic/itcl_util.c: In function ‘Itcl_SetListValue’:
./generic/itcl_util.c:502:16: warning: unused variable ‘listPtr’ [-Wunused-variable]

Here is the proposed patch

[Jan Nijtmans]

proposed fix

[Don Porter]

patch committed.