[llvm] Export LLVM_USE_SPLIT_DWARF in LLVMConfig.cmake

[JDevlieghere]

Summary

Export LLVM_USE_SPLIT_DWARF in LLVMConfig.cmake so that it can be used from standalone builds of clang and lldb. Currently, there is no way for standalone builds to know whether this option was set which means that it only applies to LLVM.

llvm/cmake/modules/LLVMConfig.cmake.in

 
 set(LLVM_BUILD_TYPE @CMAKE_BUILD_TYPE@)
 
 set(LLVM_USE_CRT_DEBUG @LLVM_USE_CRT_DEBUG@)
 set(LLVM_USE_CRT_MINSIZEREL @LLVM_USE_CRT_MINSIZEREL@)
 set(LLVM_USE_CRT_RELEASE @LLVM_USE_CRT_RELEASE@)
 set(LLVM_USE_CRT_RELWITHDEBINFO @LLVM_USE_CRT_RELWITHDEBINFO@)
 
+set(LLVM_USE_SPLIT_DWARF @LLVM_USE_SPLIT_DWARF@)
+
 set(LLVM_COMMON_DEPENDS @LLVM_COMMON_DEPENDS@)
 
 set(LLVM_AVAILABLE_LIBS @LLVM_AVAILABLE_LIBS@)
 
 @LLVM_CONFIG_LINK_LLVM_DYLIB@
 
 set(LLVM_DYLIB_COMPONENTS @LLVM_DYLIB_COMPONENTS@)