<http://webkit.org/b/77717> Makefile should provide control over output verbosity

<webkit.org/b/77717> Makefile should provide control over output verbosity

Allow the filtering of the output of our Makefile to be configured via a user default
and overriden via a command-line argument to make.

The Makefile takes the verbosity from BuildTranscriptVerbosity default in the
org.webkit.BuildConfiguration domain. The supported values are "default", "quiet"
and "noisy". "default" maintains the existing behavior of only filtering out
the setenv lines from Xcode's shell script build phases. "quiet" filters all output
through filter-build-webkit. "noisy" provides unfiltered output. The verbosity can
be overriden for a single invocation of make by specifying the VERBOSITY variable
on the make command line.

To always get full output:
defaults write org.webkit.BuildConfiguration BuildTranscriptVerbosity noisy

To always get filtered ouptut:
defaults write org.webkit.BuildConfiguration BuildTranscriptVerbosity quiet

To get full output for a single build:
make VERBOSITY=noisy

Reviewed by Dan Bernstein.

* Makefile.shared:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@106634 268f45cc-cd09-0410-ab3c-d52691b4dbfc