Changes on top of Sachin’s patch. Specifically:
 1) Refined the parsing break condition to only change the parser’s
behavior for parsing strings in binary mode (behavior of \0 outside
of strings is unchanged).
 2) Prefixed binary_zero_insert.test with ‘mysql_’ to more clearly
associate the  purpose of the test.
 3) As the input of the test contains binary zeros (0x5c00),
different text editors can visualize this sequence differently, and
Github would not display it at all. Therefore, the input itself was
consolidated into the test and created out of hex sequences to make
it easier to understand what is happening.
 4) Extended test to validate that the rows which correspond to the
INSERTS with 0x5c00 have the correct binary zero data.

Reviewed By:
===========
Andrei Elkin <andrei.elkin@mariadb.com>