crbuild: Added out directory setting.
crbuild: Printing all env vars when verbose
crbuild: Supporting Run targets.

Runs can now have targets instead of executables.
crbuild: Added support for Linux ASAN build/run.

clusterfuzz
crbuild: Factored out GYP variables into own class.

Any variable which affects how GYP generates project files is now
in it's own class.
crbuild: Saving state to intelligently regyp if necessary.

All variables that affect how GYP creates project files are stored
in ${out}/.GYP_STATE. If the current state (based upon flags, etc.)
is different than the current state then crbuild will automatically
regyp.
crbuild: Minor change to eliminate warning.

Warning was: Variable defined outside of constructor.
crbuild: idb_layout_tests -> idb-layout-tests.
crbuild: Executables can now have multiple targets.

Some exe's (like Android's content_browsertests) also need forwarder2.