h2o: only install one copy of the .so

h2o: only install one copy of the .so

I noticed that the package contained 3 identical copies of the lib:

root@52170cbc2408:/# ls -ali /usr/lib/libh2o*
 162653 -rwxr-xr-x    1 root     root        348857 Apr 25 11:50 /usr/lib/libh2o-evloop.so
 162660 -rwxr-xr-x    1 root     root        348857 Apr 25 11:50 /usr/lib/libh2o-evloop.so.0.13
 162661 -rwxr-xr-x    1 root     root        348857 Apr 25 11:50 /usr/lib/libh2o-evloop.so.0.13.6

so this commit fixes that:

root@472ad3a8404e:/# ls -ali /usr/lib/libh2o*
 289858 lrwxrwxrwx    1 root     root            21 Apr 25 12:43 /usr/lib/libh2o-evloop.so -> libh2o-evloop.so.0.13
 289859 lrwxrwxrwx    1 root     root            23 Apr 25 12:43 /usr/lib/libh2o-evloop.so.0.13 -> libh2o-evloop.so.0.13.6
 289860 -rw-r--r--    1 root     root        348857 Apr 25 12:41 /usr/lib/libh2o-evloop.so.0.1

Signed-off-by: Peter van Dijk <redacted>