Nothing was defining __solaris__ on Solaris in current build setup, and
it's not needed on Solaris 10 (released 2005) and later, which has
stdint.h. (Solaris 2.6 - 9 had inttypes.h, but no stdint.h.)
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Part-of: <https://gitlab.freedesktop.org/xorg/lib/libxcb/-/merge_requests/64>