Revert "Adding support for overriding LLVM_ENABLE_RUNTIMES for runtimes builds."

This reverts commit r371566: this doesn't correctly handle the case
where LLVM_ENABLE_RUNTIMES contains a list of values.

llvm-svn: 371579

runtimes/CMakeLists.txt

@@ -460,10 +460,6 @@ else() # if this is included from LLVM's CMake
       endif()
     endforeach()
 
-    if(NOT RUNTIMES_${name}_LLVM_ENABLE_RUNTIMES)
-      list(APPEND ${name}_extra_args -DLLVM_ENABLE_RUNTIMES=${LLVM_ENABLE_RUNTIMES})
-    endif()
-
     if(target IN_LIST LLVM_RUNTIME_BUILD_ID_LINK_TARGETS)
       list(APPEND EXTRA_ARGS STRIP_TOOL ${CMAKE_CURRENT_BINARY_DIR}/llvm-strip-link)
     endif()
@@ -486,6 +482,7 @@ else() # if this is included from LLVM's CMake
                                         -DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON
                                         -DLLVM_RUNTIMES_TARGET=${name}
                                         ${${name}_extra_args}
+                             PASSTHROUGH_PREFIXES LLVM_ENABLE_RUNTIMES
                              TOOLCHAIN_TOOLS clang lld llvm-ar llvm-ranlib llvm-nm llvm-objcopy llvm-objdump llvm-strip
                              EXTRA_TARGETS ${${name}_extra_targets}
                                            ${${name}_test_targets}