Only include SetGPUArchs in the top-level CMakeLists.txt (#713)

Fixes an issue seen when building both tests and benchmarks:
```
######################
# Configuring librmm #
######################
...
-- RMM: Building tests with GPU Architectures: 60-real;70-real;75-real;80
...
-- RMM: Building benchmarks with GPU Architectures: 60-real-real;70-real-real;75-real-real;80
-- Configuring done
CMake Error in benchmarks/CMakeLists.txt:
  Uknown CUDA architecture specifier "real-real".
```

Authors:
  - Paul Taylor (@trxcllnt)
  - Keith Kraus (@kkraus14)

Approvers:
  - Jake Hemstad (@jrhemstad)
  - Keith Kraus (@kkraus14)

URL: #713

CMakeLists.txt

@@ -83,6 +83,14 @@ set_property(CACHE RMM_LOGGING_LEVEL PROPERTY STRINGS "TRACE" "DEBUG" "INFO" "WA
                                               "CRITICAL" "OFF")
 message(STATUS "RMM: RMM_LOGGING_LEVEL = '${RMM_LOGGING_LEVEL}'")
 
+if(BUILD_TESTS OR BUILD_BENCHMARKS)
+  # Auto-detect available GPU compute architectures
+  include(${RMM_SOURCE_DIR}/cmake/Modules/SetGPUArchs.cmake)
+  message(STATUS "RMM: Building benchmarks with GPU Architectures: ${CMAKE_CUDA_ARCHITECTURES}")
+  # Only enable the CUDA language after including SetGPUArchs.cmake
+  enable_language(CUDA)
+endif()
+
 # optionally build tests
 
 if(BUILD_TESTS)

benchmarks/CMakeLists.txt

@@ -21,15 +21,8 @@ CPMFindPackage(
   GIT_SHALLOW TRUE
   OPTIONS "BENCHMARK_ENABLE_TESTING OFF" "BENCHMARK_ENABLE_INSTALL OFF")
 
-# Auto-detect available GPU compute architectures
-
-include(${RMM_SOURCE_DIR}/cmake/Modules/SetGPUArchs.cmake)
-message(STATUS "RMM: Building benchmarks with GPU Architectures: ${CMAKE_CUDA_ARCHITECTURES}")
-
 # Build options
 
-enable_language(CUDA)
-
 option(DISABLE_DEPRECATION_WARNING "Disable warnings generated from deprecated declarations." OFF)
 option(PER_THREAD_DEFAULT_STREAM "Build with per-thread default stream" OFF)
 

cmake/Modules/SetGPUArchs.cmake

@@ -72,7 +72,3 @@ list(SORT CMAKE_CUDA_ARCHITECTURES ORDER ASCENDING)
 list(POP_BACK CMAKE_CUDA_ARCHITECTURES latest_arch)
 list(TRANSFORM CMAKE_CUDA_ARCHITECTURES APPEND "-real")
 list(APPEND CMAKE_CUDA_ARCHITECTURES ${latest_arch})
-
-set(CMAKE_CUDA_ARCHITECTURES
-    ${CMAKE_CUDA_ARCHITECTURES}
-    PARENT_SCOPE)

tests/CMakeLists.txt

@@ -33,13 +33,6 @@ if(GTest_ADDED)
   add_library(GTest::gmock_main ALIAS gmock_main)
 endif()
 
-# Auto-detect available GPU compute architectures
-
-include(${RMM_SOURCE_DIR}/cmake/Modules/SetGPUArchs.cmake)
-message(STATUS "RMM: Building tests with GPU Architectures: ${CMAKE_CUDA_ARCHITECTURES}")
-
-enable_language(CUDA)
-
 # Build options
 
 option(DISABLE_DEPRECATION_WARNING "Disable warnings generated from deprecated declarations." OFF)