ORC-375: Fix libhdfs on gcc7 by adding #include <functional> two places.
ORC-375: Fix libhdfs on gcc7 by adding #include <functional> two places.

Fixes #281
Fixes #303

Signed-off-by: Owen O'Malley <54ea18af6a9d2f71f251392755b45ef039a9facd@apache.org>

majetideepak/orc,apache/orc,apache/orc,omalley/orc,majetideepak/orc,majetideepak/orc,omalley/orc,apache/orc,majetideepak/orc,omalley/orc,apache/orc,apache/orc,majetideepak/orc,omalley/orc,omalley/orc,majetideepak/orc,omalley/orc,majetideepak/orc,apache/orc,apache/orc,apache/orc,omalley/orc