[Offload] Add CMake cache to be used in AMDGPU bot (#119369)

Adds initial CMake cache definition that is similar to what we use in
one of our production buidlbots. The goal is to consolidate the
configurations and make them accessible.
This cache file is a first step and to prepare for full pipeline testing
once the new bot comes online.

Author: jplehr

offload/cmake/caches/AMDGPUBot.cmake

@@ -0,0 +1,17 @@
+# This file is meant for test builds on one basic AMDGPU buildbot only.
+
+# Install directory set to /tmp as this is a bot config
+set(CMAKE_INSTALL_PREFIX /tmp/llvm.install.test CACHE STRING "")
+
+set(LLVM_ENABLE_PROJECTS "clang;lld" CACHE STRING "")
+set(LLVM_ENABLE_RUNTIMES "compiler-rt;openmp;offload" CACHE STRING "")
+set(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR ON CACHE BOOL "")
+set(LLVM_ENABLE_ASSERTIONS ON CACHE BOOL "")
+set(LLVM_LIT_ARGS "-v --show-unsupported --timeout 100 --show-xfail -j 32" CACHE STRING "")
+set(LLVM_TARGETS_TO_BUILD "host;AMDGPU" CACHE STRING "")
+
+set(CLANG_DEFAULT_LINKER "lld" CACHE STRING "")
+
+set(CMAKE_BUILD_TYPE Release CACHE STRING "")
+set(CMAKE_C_COMPILER_LAUNCHER ccache CACHE STRING "")
+set(CMAKE_CXX_COMPILER_LAUNCHER ccache CACHE STRING "")