[CMake] add_llvm_library: Specify explicit suffix .imp to import library to avoid a warning between profile_rt-static and profile_rt-shared with lib/profile_rt.lib.

FIXME: It seems MS version of profile_rt.dll doesn't contain any export symbols.
llvm-svn: 188351

cmake/modules/AddLLVM.cmake

@@ -12,6 +12,11 @@ macro(add_llvm_library name)
 
   if( BUILD_SHARED_LIBS )
     llvm_config( ${name} ${LLVM_LINK_COMPONENTS} )
+    if (MSVC)
+      set_target_properties(${name}
+        PROPERTIES
+        IMPORT_SUFFIX ".imp")
+    endif ()
   endif()
 
   # Ensure that the system libraries always comes last on the