[cairo] _cairo_lround in tests

[Peter Weilbacher]

Hi Antoine,

seems like the _cairo_lround in test/get-path-extents.c came from you
commit. Is there no other way to fix this for Windows? Because as far
as I understand _cairo_lround is an internal cairo function and shouldn't
be used outside the library itself. It breaks compiling that test on OS/2
at least because that function isn't exported from the cairo DLL.

    Peter.