Need reviewer: No fastdebug builds by default

[Kelly O'Hair]

Need reviewer: No fastdebug builds by default

One word change. Default builds from the root will be faster due to  
not building the fastdebug images.

This change is in the open repository but will only impact our closed  
jdk builds.
Currently when building the openjdk from the top of the forest, it  
only builds one image, the so
called "product" image. This change does the same for closed jdk7  
builds.

FYI.. The fastdebug builds are built with slightly lower native  
compiler optimization levels,
all assert checking enabled, and include more debug information. The  
java classes may also
include local variable debugging information. These are mostly for  
developers but can be used
to isolate runtime issues in a jdk.

Anyone wanting both builds or the old behavior would need to use:
    make SKIP_FASTDEBUG_BUILD=false


7014634: By default, only build the product bits with a closed jdk  
build (like openjdk does)
http://cr.openjdk.java.net/~ohair/openjdk7/jdk7-build-nofastdebug/webrev/

-kto