...in preparation of teaching loplugin:redundantcast about C-style casts in
macro bodies.

TRGB_COLORDATA contained a curious cast to sal_Int32 (instead of sal_uInt32 aka
ColorData), but for one that affected (by accident?) only the fist term of the
... | ... | ... | ... expression (so the ultimate expression was of type
sal_uInt32), and for another before a83698b9
"tools: split out color macros into own header" there were two different
definitions of TRGB_COLORDATA, and only one casted to sal_Int32 (the other to
ColorData).

Change-Id: I5bfffe5614d0424202268ef7adaf6a0da61ec30a
Reviewed-on: https://gerrit.libreoffice.org/35679Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>