Log Message:
graphics/evas: Improve conftest (Fixes DragonFly)

S_IRUSR and S_IWUSR are defined in <sys/stat.h> on DragonFly, but the
conftest for the Cache Server wasn't pulling that header in.  After
patching the conftest, the package builds normally.  There was no need
to patch the source itself, so it was a bad test.