Change "configure.in".

The branches for Tru64 (ex: OSF/1) and Linux are separated,
and for Linux 'getconf GNU_LIBPTHREAD_VERSION' is used to tell between Linuxthreads and NPTL.

Define a new CPP symbol that the target OS is Linux, and use it where only the OS matters and not the threads Library.
Until now, 'HAVE_LINUXTHREADS' was used to indicate "Target is Linux" in many places.
When we support configuration with NPTL but no Linuxthreads, this misuse must cease.

Rename 'IS_LINUX' configuration variable to 'TARGET_LINUX'.

into mysql.com:/home/dlenev/src/mysql-4.1-bg8086

into mysql.com:/home/dlenev/src/mysql-4.1-bg8086

Backported from 5.0.3.

into mysql.com:/home/psergey/mysql-4.1-bug9439

into mysql.com:/space/my/mysql-4.1-build

  already (and that's the Makefile that acutally creates it)

into mysql.com:/home/psergey/mysql-4.1-look-range

minimum of lower bounds of two joined intervals.

Changed type of "Sub_part" column in SHOW KEYS from TINYINT to SMALLINT (as MAX_KEY_LENGTH=1024)
(this is the final cset with proper tests)

into mysql.com:/home/mydev/mysql-4.1-bug9188

into mysql.com:/home/mydev/mysql-4.1-bug9487

into mysql.com:/home/mydev/mysql-4.1-bug9188

into serg.mylan:/usr/home/serg/Abk/mysql-4.1

Don't abort on bootstrap if a wrong --default-storage-engine is specified

into serg.mylan:/usr/home/serg/Abk/mysql-4.1

into mysql.com:/home/jimw/my/mysql-4.1-clean

into mysql.com:/home/jimw/my/mysql-4.1-clean

into mysql.com:/home/jimw/my/mysql-4.1-clean

Fixed some casts for 64-bit systems.
Fixed a possible buffer overflow.

don't set lex->lock_option=TL_READ in the parser for SELECT

into mysql.com:/home/mydev/mysql-4.1-bug9188

for LSB init functions when they aren't available. (Bug #9852)

into serg.mylan:/usr/home/serg/Abk/mysql-4.1

into serg.mylan:/usr/home/serg/Abk/mysql-4.0

  Add fault tolerance in the scan of .ibd files at a crash recovery; formerly a single failure of readdir_get_next caused the rest of the directory to be skipped

bug#8151

into mysql.com:/space/my/mysql-4.0

into mysql.com:/space/my/mysql-4.1

into mysql.com:/space/my/mysql-4.1-build

into mysql.com:/export/space/pekka/ndb/version/my41

into mysql.com:/usr/home/ram/work/mysql-4.1