tmpdir has uppercase

Fix: don't convert mysql_tmpdir to lower case when building the path to a
temporary table


mysql-test/include/have_lowercase1.inc:
  BitKeeper file /benchmarks/ext3/TOSAVE/tsmith/bk/maint/b27653/50/mysql-test/include/have_lowercase1.inc
mysql-test/r/lowercase1.require:
  BitKeeper file /benchmarks/ext3/TOSAVE/tsmith/bk/maint/b27653/50/mysql-test/r/lowercase1.require
mysql-test/r/lowercase_mixed_tmpdir.result:
  BitKeeper file /benchmarks/ext3/TOSAVE/tsmith/bk/maint/b27653/50/mysql-test/r/lowercase_mixed_tmpdir.result
mysql-test/t/lowercase_mixed_tmpdir-master.opt:
  BitKeeper file /benchmarks/ext3/TOSAVE/tsmith/bk/maint/b27653/50/mysql-test/t/lowercase_mixed_tmpdir-master.opt
mysql-test/t/lowercase_mixed_tmpdir-master.sh:
  BitKeeper file /benchmarks/ext3/TOSAVE/tsmith/bk/maint/b27653/50/mysql-test/t/lowercase_mixed_tmpdir-master.sh
mysql-test/t/lowercase_mixed_tmpdir.test:
  BitKeeper file /benchmarks/ext3/TOSAVE/tsmith/bk/maint/b27653/50/mysql-test/t/lowercase_mixed_tmpdir.test
sql/sql_table.cc:
  When building the path for a temporary table file, do not
  convert mysql_tmpdir to lower case; lower_case_table_names
  should not apply to mysql_tmpdir.