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.