tcl: uncomment a line that causing TCL_SRC_DIR point to the workdir.

tcl: uncomment a line that causing TCL_SRC_DIR point to the workdir.

The line 'sed -i "s+${WORKDIR}+${STAGING_INCDIR}+g" tclConfig.sh'
is commented somehow in previous commit, so that TCL_SRC_DIR
point to the tcl workdir which will cause package that use it
fail to configure or compile when the tcl workdir is removed,
so uncomment it back.

(From OE-Core rev: 1037c80f63922ffdec54b0eade80ec0e89062b22)

Signed-off-by: Jackie Huang <jackie.huang@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>