Allow for configuration of the maximum number of indexes per table.
Added and used a configure.in macro.
Replaced fixed limits by the configurable limit.
Limited MyISAM indexes to its hard limit.
Fixed a bug in opt_range.cc for many indexes with InnoDB.

Tested for 2, 63, 64, 65, 127, 128, 129, 255, 256, and 257 indexes.
Testing this part of the bugfix requires rebuilding of the server 
with different options. This cannot be done with our test suite. 
Therefore I added the necessary test files to the bug report.
If you repeat the tests, please note that the ps_* tests fail for
everything but 64 indexes. This is because of differences in the 
meta data, namely field lengths for index names etc.


config/ac-macros/misc.m4:
  Bug#10932 - Building server with key limit of 128, makes test cases fail
  Allow for configuration of the maximum number of indexes per table.
  Added a macro for the new build option.
configure.in:
  Bug#10932 - Building server with key limit of 128, makes test cases fail
  Allow for configuration of the maximum number of indexes per table.
  Added a call for the new macro.
include/myisam.h:
  Bug#10932 - Building server with key limit of 128, makes test cases fail
  Allow for configuration of the maximum number of indexes per table.
  Limit the number of keys for MyISAM to its hard limit.
sql/mysql_priv.h:
  Bug#10932 - Building server with key limit of 128, makes test cases fail
  Allow for configuration of the maximum number of indexes per table.
  Stick with the optimized Bitmap<64> if indexes are limited to 64
  or lower. Otherwise use a bigger bitmap. It must be defined as a
  multiple of 8.
sql/opt_range.cc:
  Bug#10932 - Building server with key limit of 128, makes test cases fail
  Allow for configuration of the maximum number of indexes per table.
  Initialize an object element to avoid a crash when using InnoDB
  with many indexes.
sql/unireg.h:
  Bug#10932 - Building server with key limit of 128, makes test cases fail
  Allow for configuration of the maximum number of indexes per table.
  Replace the fixed limit by the configurable limit.
tests/mysql_client_test.c:
  Bug#10932 - Building server with key limit of 128, makes test cases fail
  Allow for configuration of the maximum number of indexes per table.
  Replace the fixed limit by the configurable limit.