hg: jdk/sandbox: Try to fix RC_FLAGS issue on windows.

[magnus.ihse.bursie at oracle.com]

Changeset: 8724d985c980
Author:    ihse
Date:      2018-03-14 21:52 +0100
URL:       http://hg.openjdk.java.net/jdk/sandbox/rev/8724d985c980

Try to fix RC_FLAGS issue on windows.

! make/common/JdkNativeCompilation.gmk
! make/common/NativeCompilation.gmk
! make/launcher/Launcher-java.base.gmk