[Offload][libc] Add cmake cache AMDGPU buildbot (llvm#144500)

An upcoming libc4GPU buildbot will be using this CMake cache file for
its build configuration.

Author: jplehr

offload/cmake/caches/AMDGPULibcBot.cmake

@@ -0,0 +1,20 @@
+set(CMAKE_INSTALL_PREFIX /tmp/llvm.install.test CACHE STRING "")
+
+set(CMAKE_BUILD_TYPE Release CACHE STRING "")
+set(BUILD_SHARED_LIBS ON CACHE BOOL "")
+set(CMAKE_C_COMPILER_LAUNCHER ccache CACHE STRING "")
+set(CMAKE_CXX_COMPILER_LAUNCHER ccache CACHE STRING "")
+
+set(LLVM_ENABLE_PROJECTS "clang;lld" CACHE STRING "")
+set(LLVM_ENABLE_RUNTIMES "compiler-rt;libunwind;openmp;offload" CACHE STRING "")
+set(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR ON CACHE BOOL "")
+
+set(LLVM_TARGETS_TO_BUILD "host;AMDGPU;SPIRV" CACHE STRING "")
+set(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR ON CACHE BOOL "")
+set(LLVM_ENABLE_ASSERTIONS ON CACHE BOOL "")
+
+set(CLANG_DEFAULT_LINKER "lld" CACHE STRING "")
+set(CLANG_DEFAULT_RTLIB "compiler-rt" STRING "")
+
+set(LLVM_RUNTIME_TARGETS default;amdgcn-amd-amdhsa CACHE STRING "")
+set(RUNTIMES_amdgcn-amd-amdhsa_LLVM_ENABLE_RUNTIMES "compiler-rt;libc" CACHE STRING "")