Disable C4062 on Windows.

The use of std::future introduces an implicit dependency on the PPL
subcomponent of ConcRT.  ConcRT in general is pretty noisy with
warnings, so this patch just disables one of the noisy warnings.

llvm-svn: 226590

lld/lib/ReaderWriter/CMakeLists.txt

@@ -6,6 +6,10 @@ add_subdirectory(YAML)
 
 set(LLVM_LINK_COMPONENTS object support)
 
+if (MSVC)
+  add_definitions(-wd4062) # Suppress 'warning C4062: Enumerator has no associated handler in a switch statement.'
+endif()
+
 add_lld_library(lldReaderWriter
   CoreLinkingContext.cpp
   FileArchive.cpp