CMake warnings need to be checked out at some point

[jimsch]

CMake Warning (dev) at build/_deps/project_mbedtls-src/programs/ssl/CMakeLists.txt:37 (target_sources):
Policy CMP0076 is not set: target_sources() command converts relative paths
to absolute. Run "cmake --help-policy CMP0076" for policy details. Use
the cmake_policy command to set the policy and suppress this warning.

An interface source of target "ssl_client2" has a relative path.
This warning is for project developers. Use -Wno-dev to suppress it.

CMake Warning (dev) at build/_deps/project_mbedtls-src/programs/ssl/CMakeLists.txt:44 (target_sources):
Policy CMP0076 is not set: target_sources() command converts relative paths
to absolute. Run "cmake --help-policy CMP0076" for policy details. Use
the cmake_policy command to set the policy and suppress this warning.

An interface source of target "ssl_server2" has a relative path.
This warning is for project developers. Use -Wno-dev to suppress it.

CMake Warning (dev) at build/_deps/project_mbedtls-src/programs/test/CMakeLists.txt:31 (target_sources):
Policy CMP0076 is not set: target_sources() command converts relative paths
to absolute. Run "cmake --help-policy CMP0076" for policy details. Use
the cmake_policy command to set the policy and suppress this warning.

An interface source of target "query_compile_time_config" has a relative
path.
This warning is for project developers. Use -Wno-dev to suppress it.