[cmake] Add InstrProfilingWriter to libclang_rt on Darwin

llvmBufferWriter and a few related symbols were missing from libclang_rt
on Darwin (PR26002). This should fix the problem.

Patch by Dan Peebles!

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@257110 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/cmake/Modules/CompilerRTDarwinUtils.cmake b/cmake/Modules/CompilerRTDarwinUtils.cmake
index 511361b..caa4f68 100644
--- a/cmake/Modules/CompilerRTDarwinUtils.cmake
+++ b/cmake/Modules/CompilerRTDarwinUtils.cmake
@@ -282,7 +282,8 @@
 
   set(PROFILE_SOURCES ../profile/InstrProfiling 
                       ../profile/InstrProfilingBuffer
-                      ../profile/InstrProfilingPlatformDarwin)
+                      ../profile/InstrProfilingPlatformDarwin
+		      ../profile/InstrProfilingWriter)
   foreach (os ${ARGN})
     list_union(DARWIN_BUILTIN_ARCHS DARWIN_${os}_ARCHS BUILTIN_SUPPORTED_ARCH)
     foreach (arch ${DARWIN_BUILTIN_ARCHS})