genlist: process message before restricted calc for get proper size of text and conte...

genlist: process message before restricted calc for get proper size of text and content visibled

Summary:
genlist text_get and content_get send signal for visibled or re-arrange
it's part on edc.
this singal may need to be processed before calculating item edc for
proper result.

we cannot call one only one time in realized function, because, size
must calculated before the realized callback, and user can send
customized signal in their realized callback which also need to be
processed.

Signed-off-by: SangHyeon Lee <sh10233.lee@samsung.com>