Fix a link issue I ran into trying compiling LLVM on MinGW with CMake.

Hopefully this doesn't break anyone else's build... it shouldn't unless 
the MinGW variable means something other than compiling with MinGW.

llvm-svn: 60273

llvm/cmake/modules/AddLLVM.cmake

@@ -31,7 +31,7 @@ macro(add_llvm_executable name)
   else( MSVC )
     add_dependencies(${name} llvm-config.target)
     if( MINGW )
-      target_link_libraries(${name} DbgHelp psapi)
+      target_link_libraries(${name} imagehlp psapi)
     elseif( CMAKE_HOST_UNIX )
       target_link_libraries(${name} dl)
     endif( MINGW )