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.
