mysql_install_db.sh script fixed.

Use alloc() if we don't need original string (avoid copy)
Removed not needed test of str_length in sql_string.cc

This is a post-fix for MDEV-16542

Assign "SELECT" to the table before it usage.

tests fixed.

tests fixed.

New version of PAM plugin (v2.0) added along with the old v1.0.
There the pam module is isolated in the auth_pam_tool application so
cannot crash the server.

For some reason, some of these suppressions would fail to suppress
when the code is compiled with clang 6.0, Debug and -DWITH_ASAN=ON.
Possibly it is related to the number of .* or the length of the
regular expression strings.

Before attempting to create an index, copy any fields from
dict_table_t, because the table would be freed after a failed
index creation.

	NULL values when there is no DEFAULT

- Merged the alter_non_null test case to alter_not_null test case.
Renamed the alter_non_null_debug to alter_not_null_debug test case

Correct 898a8c3c to work when newer debhelper-10.2 is installed from
xenial-backports (or jessie-backports).

Use gcc version instead of debproxy version, this is likely a gcc
issue (as disabling LTO and gcc's linker plugin fixes it).

* ignore CHECK constraint for historical rows;
* FOREIGN KEY test case.

TODO:
MDEV-16301 IB: use real table name for error messages on ALTER

Closes tempesta-tech/mariadb#491
Closes #748

MDEV-15947 ASAN heap-use-after-free in Item_ident::print or in my_strcasecmp_utf8 or unexpected ER_BAD_FIELD_ERROR upon call of stored procedure reading from versioned table

Closes #728

MDEV-15645 Assertion `table->insert_values' failed in write_record upon REPLACE into a view with underlying versioned table

Right temporary storage for system versioning operations is table->record[2],
not table->insert_values

Closes #712

RBR not versioned -> versioned

do it for all write_row events, not only for WRITE_ROWS_EVENT_V1

Building this plugin which requires run-time access to network, uses a lot
of disk space and is slow was already partially disabled. This way we
also ensure that on cmake level it never runs even if it out of some
autodetection reason at times thought it could run.

This fixes the error message:
  fatal: unable to access 'https://github.com/awslabs/aws-sdk-cpp.git/':
  Problem with the SSL CA cert (path? access rights?)

Fixes errors on Travis like:
  cp: error writing debian/libmariadbd19//usr/lib/x86_64-linux-gnu/
  libmariadbd.so.19: No space left on device

This complements commit ecb0e0ad that
disabled a bunch of plugins from being built on Travis-CI (due to time
and disk space saving reasons).

When the plugins are not built, the packaging phase will fail due to
missing files. This change omits the files from packaging to the process
can complete successfully.