inprocess_cache_get(): silence compiler warning.

subversion/libsvn_subr/cache-inprocess.c: In function 'inprocess_cache_get':
subversion/libsvn_subr/cache-inprocess.c:217: warning: 'size' may be used uninitialized in this function

* subversion/libsvn_subr/cache-inprocess.c
  (inprocess_cache_get):
    Set size to 0 to avoid a compiler warning.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1469519 13f79535-47bb-0310-9956-ffa450edef68