[mlir] Fix CMake build for libMLIR.so with MLIR_ENABLE_CUDA_RUNNER=ON

[christopherbate]

Summary

When configured with LLVM_BUILD_LLVM_DYLIB=ON and MLIR_ENABLE_CUDA_RUNNER=ON,
the build will fail at the link stage of libMLIR.so because symbols
for the CUDA driver libcuda.so are not available but required by
MLIRGPUTransforms. In the future, this should probably evolve to link
the library stubs/libcuda.so shipped with the CUDA toolkit rather than
the system libcuda.so.

[mehdi_amini]

This option (MLIR_ENABLE_CUDA_RUNNER) looks terribly named unfortunately.

mlir/tools/mlir-shlib/CMakeLists.txt

foreach (lib ${mlir_libs})
   # list(APPEND _DEPS  $<TARGET_PROPERTY:${lib},LINK_LIBRARIES>)
 endforeach ()
 
 if(MLIR_LINK_MLIR_DYLIB)
   set(INSTALL_WITH_TOOLCHAIN INSTALL_WITH_TOOLCHAIN)
 endif()
 
 if(LLVM_BUILD_LLVM_DYLIB)
+  if(MLIR_ENABLE_CUDA_RUNNER)
+    find_library(CUDA_DRIVER_LIBRARY cuda REQUIRED)
+    list(APPEND _DEPS ${CUDA_DRIVER_LIBRARY})
+  endif()
+
   add_mlir_library(
     MLIR
     SHARED
     ${INSTALL_WITH_TOOLCHAIN}
     mlir-shlib.cpp
     ${_OBJECTS}
     LINK_LIBS
     ${_DEPS}