clean up engine repo cmake warnings

These errors get reported on Ubuntu and SuSE builds when the engine cmake is run

Cloning into 'mariadb-columnstore-engine'...
remote: Counting objects: 22901, done.
remote: Compressing objects: 100% (160/160), done.
remote: Total 22901 (delta 72), reused 0 (delta 0), pack-reused 22741
Receiving objects: 100% (22901/22901), 103.89 MiB | 5.33 MiB/s, done.
Resolving deltas: 100% (12660/12660), done.
Checking connectivity... done.
error: pathspec 'devel_1.0' did not match any file(s) known to git.
SERVER_BUILD_INCLUDE_DIR = /home/builder/mariadb-columnstore-server/mariadb-columnstore-engine/../include
SERVER_SOURCE_ROOT_DIR = /home/builder/mariadb-columnstore-server/mariadb-columnstore-engine/..
CMake Warning (dev) at dbcon/ddlpackage/CMakeLists.txt:35 (add_dependencies):
Policy CMP0046 is not set: Error on non-existent dependency in
add_dependencies. Run "cmake --help-policy CMP0046" for policy details.
Use the cmake_policy command to set the policy and suppress this warning.

The dependency target
"/home/builder/mariadb-columnstore-server/mariadb-columnstore-engine/dbcon/ddlpackage/ddl-gram.cpp"
of target "ddlpackage" does not exist.
This warning is for project developers. Use -Wno-dev to suppress it.

CMake Warning (dev) at dbcon/ddlpackage/CMakeLists.txt:35 (add_dependencies):
Policy CMP0046 is not set: Error on non-existent dependency in
add_dependencies. Run "cmake --help-policy CMP0046" for policy details.
Use the cmake_policy command to set the policy and suppress this warning.

The dependency target
"/home/builder/mariadb-columnstore-server/mariadb-columnstore-engine/dbcon/ddlpackage/ddl-scan.cpp"
of target "ddlpackage" does not exist.
This warning is for project developers. Use -Wno-dev to suppress it.

CMake Warning (dev) at dbcon/dmlpackage/CMakeLists.txt:35 (add_dependencies):
Policy CMP0046 is not set: Error on non-existent dependency in
add_dependencies. Run "cmake --help-policy CMP0046" for policy details.
Use the cmake_policy command to set the policy and suppress this warning.

The dependency target
"/home/builder/mariadb-columnstore-server/mariadb-columnstore-engine/dbcon/dmlpackage/dml-gram.cpp"
of target "dmlpackage" does not exist.
This warning is for project developers. Use -Wno-dev to suppress it.

CMake Warning (dev) at dbcon/dmlpackage/CMakeLists.txt:35 (add_dependencies):
Policy CMP0046 is not set: Error on non-existent dependency in
add_dependencies. Run "cmake --help-policy CMP0046" for policy details.
Use the cmake_policy command to set the policy and suppress this warning.

The dependency target
"/home/builder/mariadb-columnstore-server/mariadb-columnstore-engine/dbcon/dmlpackage/dml-scan.cpp"
of target "dmlpackage" does not exist.
This warning is for project developers. Use -Wno-dev to suppress it.