Fix: CMAKE_MODULE_PATH contents is being overriden with -D contents, not merged with

[gorloffslava]

Current code defines the CMAKE_MODULE_PATH as a cache variable[1]. As a result, if one passes the -DCMAKE_MODULE_PATH=<something> to the cmake invocation, its contents override the paths to netcdf-bundled cmake modules. Based on code and attempt to use Shell-PATH-like expansion, it looks as unintended behavior. Moreover, it's quite common in CI/CD systems to pass extra cmake module paths (e.g., we have to do so for AWS SDKs, on which netcdf depends optionally). This tiny fix replaces that with list(APPEND) which adds paths to netcdf-provided modules to the user-passed -DCMAKE_MODULE_PATH. At the same time, if user doesn't passes this variable - the previous behavior is preserved, as netcdf paths will be added to that CMAKE_MODULE_PATH currently holds (if netcdf is built as standalone project and not as a subproject of our project - it's an empty list).

References:
[1]

netcdf-c/CMakeLists.txt

Line 21 in d694d38

set(CMAKE_MODULE_PATH "${CMAKE_MODULE_PATH};${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules/;${PROJECT_SOURCE_DIR}/cmake"

[CLAassistant]

All committers have signed the CLA.

[WardF]

The failures are unrelated to the PR, and are part of an issue we're fixing on the Unidata side. This looks good and will be merged shortly.

[BwL1289]

@WardF thank you!

[gorloffslava]

@WardF thank you!