IMPALA-4686: Fix schema output for INT96 columns in parquet-reader tool
IMPALA-4686: Fix schema output for INT96 columns in parquet-reader tool

Instead of manually mapping the types we can just look them up in the
thrift map.

Testing: I tested this change manually by compiling the tool and running
it on a parquet file that had a INT96 column. Here is the relevant
output:

Schema:
id  INT32
bool_col  BOOLEAN
tinyint_col  INT32
smallint_col  INT32
int_col  INT32
bigint_col  INT64
float_col  FLOAT
double_col  DOUBLE
date_string_col  BYTE_ARRAY
string_col  BYTE_ARRAY
timestamp_col  INT96
year  INT32
month  INT32

We only use this tool in one test currently, which calls it to make sure
that a parquet-file can be parsed by it. This implies that we have tests
that it compiles, but we don't make use of its output currently.

Change-Id: I5d92f5556554c71461a93fe0d598bb69f91cce51
Reviewed-on: http://gerrit.cloudera.org:8080/5536
Reviewed-by: Lars Volker <4d73c29a4561048ce85fa0051bb7a6d201781159@cloudera.com>
Reviewed-by: Matthew Jacobs <df2fa7c39d141dc5dc5589fed74180e757ed6c9a@cloudera.com>
Tested-by: Internal Jenkins

michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,michaelhkw/incubator-impala,cloudera/Impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala