[cmake] Fix dependencies.

* Use CMAKE_DL_LIBS instead of hard-coded `dl`.
* Use Threads::Threads instead of `pthread`.
* Drop `rt` dep.
* Find libdrm via pkgconfig (consistent to how other ROCm projects do it as documented here: https://github.com/ROCm/TheRock/blob/main/docs/development/dependencies.md#libdrm)

src/CMakeLists.txt

@@ -78,7 +78,12 @@ set(${AMD_SMI}_VERSION_BUILD "0")
 message("SOVERSION: ${SO_VERSION_STRING}")
 
 add_library(${AMD_SMI} ${SRC_LIST} ${INC_LIST})
-target_link_libraries(${AMD_SMI} pthread rt dl ${DRM_LIBRARIES} ${AMDGPU_DRM_LIBRARIES})
+target_link_libraries(${AMD_SMI} PRIVATE
+    PkgConfig::DRM
+    PkgConfig::DRM_AMDGPU
+    Threads::Threads
+    ${CMAKE_DL_LIBS}
+)
 target_include_directories(${AMD_SMI} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR} ${PROJECT_SOURCE_DIR}/rocm_smi/include
                                               ${PROJECT_SOURCE_DIR}/common/shared_mutex ${ACA_INC_DIR})