wmemset was being used to fill the row buffers.
wmemset was intended  to  fill the buffer with
16-bit UCS2 pad values.  However,  the  64-bit
version of wmemset uses 32-bit wide characters
and thus filled the buffer incorrectly. In some
cases, the null  byte  map would be overwritten,
causing ctype_utf8.test and ibmdb2i_rir.test to
fail, giving the error message CPF5035.

This patch eliminates the use of wmemset to fill
the row buffer. wmemset has  been  replaced with
memset16, which always  fills  memory with 16-bit
values.

storage/ibmdb2i/db2i_conversion.cc:
  Bug#44811 Tests with utf8 charset fail with ibmdb2i on 64bit MySQL
  
  Eliminate the use of wmemset to fill
  the row buffer. Replace wmemset with
  memset16, which always  fills  memory
  with 16-bit values.
storage/ibmdb2i/db2i_misc.h:
  Bug#44811 Tests with utf8 charset fail with ibmdb2i on 64bit MySQL
  
  Eliminate the use of wmemset to fill
  the row buffer. Replace wmemset with
  memset16, which always  fills  memory
  with 16-bit values.