RFR(Trivial) 8209826 Undefined reference to os::write after JDK-8209657 (filemap.hpp cleanup)

[Ioi Lam]

https://bugs.openjdk.java.net/browse/JDK-8209826

The fix is trivial:

diff -r e77d7687c831 src/hotspot/share/memory/filemap.cpp
--- a/src/hotspot/share/memory/filemap.cpp Fri Aug 17 13:53:53 2018 -0700
+++ b/src/hotspot/share/memory/filemap.cpp Tue Aug 21 19:56:14 2018 -0700
@@ -44,7 +44,7 @@
  #include "prims/jvmtiExport.hpp"
  #include "runtime/arguments.hpp"
  #include "runtime/java.hpp"
-#include "runtime/os.hpp"
+#include "runtime/os.inline.hpp"
  #include "runtime/vm_version.hpp"
  #include "services/memTracker.hpp"
  #include "utilities/align.hpp"

Now I wonder why we enable precompiled headers by default on Linux ...
for me it isn't faster and the only thing it has accomplished is to
cause build failures (2x in a week).

Thanks
- Ioi