hg: build-infra/jdk9/hotspot: * Move symbol cflags to JVM_CFLAGS_SYMBOLS in configure.

[magnus.ihse.bursie at oracle.com]

Changeset: 566dd099989d
Author:    ihse
Date:      2016-01-18 12:22 +0100
URL:       http://hg.openjdk.java.net/build-infra/jdk9/hotspot/rev/566dd099989d

* Move symbol cflags to JVM_CFLAGS_SYMBOLS in configure.
* Stop using HOTSPOT_DEBUG_LEVEL whenever not needed.

! makefiles/Common.gmk
! makefiles/FlagOverrides.gmk