Revert "[libclc] Move CMake for prepare_builtins to a subdirectory (llvm#148815)"

This reverts commit 8a7a648.  It broke
standalone builds since the necessary variables are now limited in scope
to `libclc/utils` while they are used in the top-level CMakeLists.

Author: mgorny

libclc/CMakeLists.txt

@@ -164,14 +164,34 @@ endif()
 
 list( SORT LIBCLC_TARGETS_TO_BUILD )
 
+# Construct LLVM version define
+set( LLVM_VERSION_DEFINE "-DHAVE_LLVM=0x${LLVM_VERSION_MAJOR}0${LLVM_VERSION_MINOR}" )
+
 # This needs to be set before any target that needs it
 # We need to use LLVM_INCLUDE_DIRS here, because if we are linking to an
 # llvm build directory, this includes $src/llvm/include which is where all the
 # headers are not $build/include/ which is what LLVM_INCLUDE_DIR is set to.
 include_directories( ${LLVM_INCLUDE_DIRS} )
 
-# Configure prepare_builtins
-add_subdirectory( utils )
+# Setup prepare_builtins tools
+set(LLVM_LINK_COMPONENTS
+  BitReader
+  BitWriter
+  Core
+  IRReader
+  Support
+)
+if( LIBCLC_STANDALONE_BUILD )
+  add_llvm_executable( prepare_builtins utils/prepare-builtins.cpp )
+  set( prepare_builtins_exe prepare_builtins )
+  set( prepare_builtins_target prepare_builtins )
+else()
+  add_llvm_utility( prepare_builtins utils/prepare-builtins.cpp )
+  setup_host_tool( prepare_builtins PREPARE_BUILTINS prepare_builtins_exe prepare_builtins_target )
+endif()
+target_compile_definitions( prepare_builtins PRIVATE ${LLVM_VERSION_DEFINE} )
+# These were not properly reported in early LLVM and we don't need them
+target_compile_options( prepare_builtins PRIVATE -fno-rtti -fno-exceptions )
 
 # Setup arch devices
 set( r600--_devices cedar cypress barts cayman )