* module/system/base/optimize.scm: New module.
* module/Makefile.am (SOURCES):
* am/bootstrap.am (SOURCES): Add new module.
* module/language/tree-il/optimize.scm (tree-il-optimizations): Rename
from tree-il-default-optimization-options. Directly specify the
optimization level at which a pass should be enabled.
* module/language/cps/optimize.scm (cps-optimizations): Likewise, rename
from cps-default-optimization-options.
* module/scripts/compile.scm (%options, show-optimization-help): Adapt
to use new module.
