libcss-0.4.0-bp151.3.1

- Fix RPM groups.

- Update to version 0.4.0
  * Due to the change from CSS2 overflow to CSS3 overflow properties, the
  computed style access functions for overflow properties have changed.
  The overflow property is removed.  Added are overflow-x and overflow-y
  properties.  (The overflow shorthand property now sets overflow-x and
  overflow-y.)
  This change affects the following functions:
    Removed from   include/libcss/computed.h    --  css_computed_overflow()
    Added to       include/libcss/computed.h    --  css_computed_overflow_x()
    Added to       include/libcss/computed.h    --  css_computed_overflow_y()

- libcss-buildopts.patch: Do not define BSD_SOURCE but
  GNU_SOURCE (fioxes build fail in factory)
- use -std=gnu99 instead of -std=c99.
- Disable -Werror

- Cleanup with spec-cleaner

- Initial import of libcss, inspired from Fedora package