[CMake] Handle common options in runtimes build

[phosek]

Summary

All the existing runtimes relies on flags which are set by AddLLVM and HandleLLVMOptions. While these get included by each individual runtime in the standalone case, when being built as part of LLVM runtimes we need to include these in the top-level CMake file.

[beanz]

LGTM.

llvm/trunk/runtimes/CMakeLists.txt

if(${CMAKE_SOURCE_DIR} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR})
   # Setting these variables will allow the sub-build to put their outputs into
   # the library and bin directories of the top-level build.
   set(LLVM_LIBRARY_OUTPUT_INTDIR ${LLVM_LIBRARY_DIR})
   set(LLVM_RUNTIME_OUTPUT_INTDIR ${LLVM_TOOLS_BINARY_DIR})
 
   # This variable makes sure that e.g. llvm-lit is found.
   set(LLVM_MAIN_SRC_DIR ${LLVM_BUILD_MAIN_SRC_DIR})
 
+  # Handle common options used by all runtimes.
+  include(AddLLVM)
+  include(HandleLLVMOptions)
+
   foreach(entry ${runtimes})
     get_filename_component(projName ${entry} NAME)
 
     # TODO: Clean this up as part of an interface standardization
     string(REPLACE "-" "_" canon_name ${projName})
     string(TOUPPER ${canon_name} canon_name)
     # The subdirectories need to treat this as standalone builds
     set(${canon_name}_STANDALONE_BUILD On)