Make ./snappy_unittest pass without "srcdir" being defined.
Make ./snappy_unittest pass without "srcdir" being defined.

Previously, snappy_unittests would read from an absolute path /testdata/..;
convert it to use a relative path instead.

Patch from Marc-Antonie Ruel.

R=maruel


git-svn-id: 29021146237193d7b18c96610dd9df40103866e6@72 03e5f5b5-db94-4691-08a0-1a8bf15f6143

apage43/snappy,ukoethe/snappy,couchbase/snappy,apage43/snappy,ukoethe/snappy,b3sigma/snappy,b3sigma/snappy,ukoethe/snappy,ukoethe/snappy,apage43/snappy,couchbase/snappy,apage43/snappy,couchbase/snappy,b3sigma/snappy,b3sigma/snappy,couchbase/snappy,b3sigma/snappy