Set CMAKE_BUILD_WITH_INSTALL_RPATH for Fuchsia runtimes

This doesn't make any difference since we don't use RPATH/RUNPATH
on Fuchsia but it avoids the CMake error when re-linking libraries
while building with Ninja.

Differntial Revision: https://reviews.llvm.org/D46610

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@331833 91177308-0d34-0410-b5e6-96231b3b80d8

cmake/caches/Fuchsia-stage2.cmake

@@ -67,6 +67,7 @@ endif()
 foreach(target x86_64;aarch64)
   set(RUNTIMES_${target}-fuchsia_CMAKE_SYSTEM_NAME Fuchsia CACHE STRING "")
   set(RUNTIMES_${target}-fuchsia_CMAKE_BUILD_TYPE ${FUCHSIA_RUNTIMES_BUILD_TYPE} CACHE STRING "")
+  set(RUNTIMES_${target}-fuchsia_CMAKE_BUILD_WITH_INSTALL_RPATH ON CACHE STRING "")
   set(RUNTIMES_${target}-fuchsia_CMAKE_ASM_FLAGS ${FUCHSIA_${target}_C_FLAGS} CACHE PATH "")
   set(RUNTIMES_${target}-fuchsia_CMAKE_C_FLAGS ${FUCHSIA_${target}_C_FLAGS} CACHE PATH "")
   set(RUNTIMES_${target}-fuchsia_CMAKE_CXX_FLAGS ${FUCHSIA_${target}_CXX_FLAGS} CACHE PATH "")