[Libomptarget] Remove dependency on the DeviceRTL from the GPU plugins

The GPU plugins have a dependency on the device libraries. Sometimes we
cannot build the device libraries because the user does not have a valid
`clang` to use or it was explicitly disabled. Currently this leads to a
transitive failure because we cannot meet this dependency. This patch
simply removes that dependency.

Fixes #60457

Reviewed By: tianshilei1992

Differential Revision: https://reviews.llvm.org/D143196

(cherry picked from commit 9f650ae)

Author: jhuber6

openmp/libomptarget/plugins-nextgen/amdgpu/CMakeLists.txt

@@ -90,7 +90,6 @@ add_llvm_library(omptarget.rtl.amdgpu.nextgen SHARED
 
   NO_INSTALL_RPATH
 )
-add_dependencies(omptarget.rtl.amdgpu.nextgen omptarget.devicertl.amdgpu)
 
 target_include_directories(
   omptarget.rtl.amdgpu.nextgen

openmp/libomptarget/plugins-nextgen/cuda/CMakeLists.txt

@@ -85,7 +85,6 @@ else()
     NO_INSTALL_RPATH
   )
 endif()
-add_dependencies(omptarget.rtl.cuda.nextgen omptarget.devicertl.nvptx)
 
 # Install plugin under the lib destination folder.
 install(TARGETS omptarget.rtl.cuda.nextgen LIBRARY DESTINATION "${OPENMP_INSTALL_LIBDIR}")

openmp/libomptarget/plugins/amdgpu/CMakeLists.txt

@@ -90,7 +90,6 @@ add_llvm_library(omptarget.rtl.amdgpu SHARED
 
   NO_INSTALL_RPATH
 )
-add_dependencies(omptarget.rtl.amdgpu omptarget.devicertl.amdgpu)
 
 target_include_directories(
   omptarget.rtl.amdgpu

openmp/libomptarget/plugins/cuda/CMakeLists.txt

@@ -82,7 +82,6 @@ else()
     NO_INSTALL_RPATH
   )
 endif()
-add_dependencies(omptarget.rtl.cuda omptarget.devicertl.nvptx)
 
 # Install plugin under the lib destination folder.
 install(TARGETS omptarget.rtl.cuda LIBRARY DESTINATION "${OPENMP_INSTALL_LIBDIR}")