fixes http://code.google.com/p/drmemory/issues/detail?id=1025 + add FILE_SHARE_WRITE to os_file_exists() to prevent sharing   violations on simulataneous access
fixes http://code.google.com/p/drmemory/issues/detail?id=1025
+ add FILE_SHARE_WRITE to os_file_exists() to prevent sharing
  violations on simulataneous access

git-svn-id: ed337ca7cdb08c0ba29d8fe58632bb7686892c2d@1582 49cc7528-f6fd-11dd-9d1a-b59b2e1864b6

rnk/dynamorio,rnk/dynamorio,rnk/dynamorio,rnk/dynamorio,rnk/dynamorio