Add config file for cmake to find UCC on system

[zasdfgbnm-nvidia]

This PR makes the installation script writes cmake config files to ${prefix}/lib/cmake/ucc so that cmake projects can easily find UCC installed on the system. PyTorch uses cmake, so this will be helpful for PyTorch to integrate the ucc backend to upstream.

I will add the same thing for UCX later. This PR is tested by: https://github.com/zasdfgbnm/cmake-ucx-ucc, please let me know if you want cmake testes to be included in this repository as well.

[mellanox-github]

Can one of the admins verify this patch?

[Sergei-Lebedev]

pls add copyright to new files

[Sergei-Lebedev]

remove extra parenthesis

[zasdfgbnm]

fixed

[zasdfgbnm]

I have added copyright info, I also updated the commit title.

[vspetrov]

@zasdfgbnm-nvidia thanks for the PR. I have a couple of minor comments:

1. Can we support project name with capital letters? Currently when i need to set custom search path i'm setting -Ducc_DIR= which kind of looks unorthodox. I'd prefer it be: UCC_DIR.
2. Why cmake-* files go under install/lib? Is it common? Wouldn't it be more natural to put it, e.g., in "install/share" ?

[zasdfgbnm]

Re @vspetrov

1. ucc_DIR vs UCC_DIR actually depends on whether you are doing find_package(ucc) or find_package(UCC), if your variable name and package name matches, for both cases, CMake should be able to find the correct package. The only difference is inside your cmake scripts, whether you should use ucc_INCLUDE_DIRS vs Ucc_INCLUDE_DIRS vs UCC_INCLUDE_DIRS and target_link_libraries(mytarget ucc::ucc) vs target_link_libraries(mytarget Ucc::Ucc) vs target_link_libraries(mytarget UCC::UCC). I updated my PR, and currently it is doing UCC_INCLUDE_DIRS and target_link_libraries(mytarget ucc::ucc). Let me know if this works for you.

2. Yes, this is a standard path, for example on my system

gaoxiang@sunnyvale ~/ucc cmake $ ls /usr/share/cmake/
 bash-completion   Modules
gaoxiang@sunnyvale ~/ucc cmake $ ls /usr/lib/cmake/
 AccountsQt5                                            KF5Config                     libmongoc-1.0
 Analitza5                                              KF5ConfigWidgets              libmsym
 AppStreamQt                                            KF5ContactEditor              LibNotificationManager
 arpack-ng                                              KF5Contacts                   libssh
 Astro                                                  KF5CoreAddons                 LibTaskManager
 avogadrolibs                                           KF5Crash                      libwebsockets
 Boost-1.76.0                                           KF5DAV                        libxml2
 boost_atomic-1.76.0                                    KF5DBusAddons                 libzip
 boost_chrono-1.76.0                                    KF5Declarative                llvm
.....
gaoxiang@sunnyvale ~/ucc cmake $ tree /usr/lib/cmake/
/usr/lib/cmake/
|-- AccountsQt5
|   |-- AccountsQt5Config.cmake
|   `-- AccountsQt5ConfigVersion.cmake
|-- Analitza5
|   |-- Analitza5Config.cmake
|   |-- Analitza5ConfigVersion.cmake
|   |-- Analitza5Targets-noconfig.cmake
|   `-- Analitza5Targets.cmake
|-- AppStreamQt
|   |-- AppStreamQtConfig.cmake
|   `-- AppStreamQtConfigVersion.cmake
|-- Astro
|   |-- AstroConfig.cmake
|   |-- AstroConfigVersion.cmake
|   |-- AstroTargets-noconfig.cmake
|   `-- AstroTargets.cmake
......

For another example see: https://github.com/nih-at/libzip/blob/master/CMakeLists.txt#L442

[vspetrov]

thanks, looks good

[vspetrov]

@zasdfgbnm please rebase

[zasdfgbnm]

@vspetrov rebased