'make bdb2' tests only BDB2
'make ldbm' tests only LDBM
Fix up scripts (previous changes broke BDB2 testing)

Remove disable write sync (dbcachenowsync) in master (for concurrency test).

Modify slapd_tester to use pid_t and wait macros.  May need to
implement additional macros in ac/wait.h (in addition to
WEXITSTATUS and WIFEXITED).

Mainly updated back-bdb2, back-passwd, back-shell to use slap_get_time().

address.  Useful for running multiple servers in a virtual hosting
environment.
Modified test001-ldif2ldbm to verify this functionality.  Assumes
localhost is 127.0.0.1.

These functions require their arguments to be in the range of `unsigned char'.

Building tests/progs/*.c in the main build process.
==> Test-suite must be called by 'make test', or 'make test-bdb2'

Slight adaption of concurrency-test to enable even more writers/readers.

  correctness of locking schemas in backends.
In back-bdb2 open NEXTID during startup and close at shutdown.

slapd server timing via a new slapd command line option '-t'.

Use $BACKEND instead of BDB2.  Fallback to LDBM if $BACKEND is not BDB2.

Integration into ./configure ( --enable-bdb2 ).
Adaptation of the test-suite ( 'make' -> ldbm; 'make bdb2-local' -> bdb2 ).
Minor fixes in slapd/libldbm.

initialization after reading slapd.conf, and before starting the daemon

introduction of pid/agrs parameters to the test-suite slapd.conf files;
creation of sub-directory test/var for storage of pid/args files during test;
update of the slapd and slapd.conf man pages.
(The change reduces dependency on ldapconfig.h, since SLAPD_PIDEXT
 and SLAPD_ARGSEXT are deleted from the code.)