add_tablegen: Remove LLVM_ENABLE_OBJLIB

- It doesn't work if `ALL_FILES` has `$<TARGET_OBJECTS>` with Makefile generator.
- It was a micro-optimization in the ancient age. (introduced in rGe6bc093b42ff)

llvm/cmake/modules/TableGen.cmake

@@ -143,12 +143,6 @@ macro(add_tablegen target project)
   set(${target}_OLD_LLVM_LINK_COMPONENTS ${LLVM_LINK_COMPONENTS})
   set(LLVM_LINK_COMPONENTS ${LLVM_LINK_COMPONENTS} TableGen)
 
-  # CMake doesn't let compilation units depend on their dependent libraries on some generators.
-  if(NOT CMAKE_GENERATOR MATCHES "Ninja" AND NOT XCODE)
-    # FIXME: It leaks to user, callee of add_tablegen.
-    set(LLVM_ENABLE_OBJLIB ON)
-  endif()
-
   add_llvm_executable(${target} DISABLE_LLVM_LINK_LLVM_DYLIB
     ${ADD_TABLEGEN_UNPARSED_ARGUMENTS})
   set(LLVM_LINK_COMPONENTS ${${target}_OLD_LLVM_LINK_COMPONENTS})