Fixes the following bug:

- Bug #32125: Database crash due to ha_innodb.cc:3896: ulint convert_search_mode_to_innobase

  When unknown find_flag is encountered in convert_search_mode_to_innobase()
  do not call assert(0); instead queue a MySQL error using my_error() and
  return the error code PAGE_CUR_UNSUPP. Change the functions that call
  convert_search_mode_to_innobase() to handle that error code by "canceling"
  execution and returning appropriate error code further upstream.


storage/innobase/dict/dict0dict.c:
  Applied InnoDB snapshot innodb-5.1-ss2093
  
  Revision r2092:
  Remove the unused function innobase_convert_from_filename() that was
  inadvertently added in r590.
storage/innobase/handler/ha_innodb.cc:
  Applied InnoDB snapshot innodb-5.1-ss2093
  
  Revision r2088:
  Fix Bug#32125 (http://bugs.mysql.com/32125)
  "Database crash due to ha_innodb.cc:3896: ulint convert_search_mode_to_innobase":
  
  When unknown find_flag is encountered in convert_search_mode_to_innobase()
  do not call assert(0); instead queue a MySQL error using my_error() and
  return the error code PAGE_CUR_UNSUPP. Change the functions that call
  convert_search_mode_to_innobase() to handle that error code by "canceling"
  execution and returning appropriate error code further upstream.
  
  Approved by:	Heikki (via IM)
  
  
  
  Revision r2093:
  convert_search_mode_to_innobase(): Add the missing case label
  HA_READ_MBR_EQUAL that was forgotten in r2088.
  
  
  Revision r2089:
  Non-functional change: convert the switch in convert_search_mode_to_innobase()
  to the InnoDB coding style.
  
  
  Revision r2092:
  Remove the unused function innobase_convert_from_filename() that was
  inadvertently added in r590.
storage/innobase/include/page0cur.h:
  Applied InnoDB snapshot innodb-5.1-ss2093
  
  Revision r2088:
  Fix Bug#32125 (http://bugs.mysql.com/32125)
  "Database crash due to ha_innodb.cc:3896: ulint convert_search_mode_to_innobase":
  
  When unknown find_flag is encountered in convert_search_mode_to_innobase()
  do not call assert(0); instead queue a MySQL error using my_error() and
  return the error code PAGE_CUR_UNSUPP. Change the functions that call
  convert_search_mode_to_innobase() to handle that error code by "canceling"
  execution and returning appropriate error code further upstream.
  
  Approved by:	Heikki (via IM)