Review request for 6915413 Module build: building of specified jdk components instead of all

[Mandy Chung]

Hi Alan, Kelly,

Can you review the change for:
   6915413 Module build: building of specified jdk components instead of all

Webrev at:
   http://cr.openjdk.java.net/~mchung/6915413/webrev.00/

A new file, make/common/Subdirs.gmk, is added to handle the
recursive building of subdirectories.  Makefiles that call
SUBDIRS-loop are modified to include make/common/Subdirs.gmk
after SUBDIRS* variables are defined.

No change to the usual way in building JDK, i.e.
   gnumake all - building the entire JDK

What's new is described in the comment in make/common/Subdirs.gmk:

# SUBDIRS          subdirs for the base module always get built
# SUBDIRS_<group>  subdirs for the named group
#
# By default, subdirs specified in the SUBDIRS and all SUBDIRS_* 
# variables will be built.
# 
# BUILD_MODULES variable can be used to specify one or more groups
# to be built (BUILD_MODULES=all will build all groups).
#
# Variables of the currently supported groups are:
#  SUBDIRS_desktop    
#  SUBDIRS_management
#  SUBDIRS_enterprise
#  SUBDIRS_misc
#  SUBDIRS_tools
# 
# Eventually we want to restructure the make directory
# according to these grouping (e.g. make/desktop/...) and
# the SUBDIRS_<group> variables would not be needed.
# 
# To build the desktop and tools groups only, you can do:
# gnumake BUILD_MODULES="desktop tools" ...
# 

When we finalize the list of jdk modules/profiles, we may
update the supported groups to reflect the final grouping
and also create only the modules belonging to that group
under <outputdir>/modules/ directory.

Thanks
Mandy