The autotools-based build system has been superseded and
is being removed in order to ease the maintenance burden on
developers tweaking and maintaining the build system.

In order to support tools that need to extract the server
version, a new file that (only) contains the server version,
called VERSION, is introduced. The file contents are human
and machine-readable. The format is:

MYSQL_VERSION_MAJOR=5
MYSQL_VERSION_MINOR=5
MYSQL_VERSION_PATCH=8
MYSQL_VERSION_EXTRA=-rc

The CMake based version extraction in cmake/mysql_version.cmake
is changed to extract the version from this file. The configure
to CMake wrapper is retained for backwards compatibility and to
support the BUILD/ scripts. Also, a new a makefile target
show-dist-name that prints the server version is introduced.

VERSION:
  Add top-level version file.
cmake/mysql_version.cmake:
  Get version information from the top-level VERSION file.
  Do not cache the version components (MAJOR_VERSION, etc).
  Add MYSQL_RPM_VERSION as a replacement for MYSQL_U_SCORE_VERSION.