Optimize use & namespaces lookups

[theofidry]

I noticed whilst debugging the scoping of a Box class that if a symbol is always resolved even if the name, namespace and file don't change. This is a bit of a loss and could be optimized.

[theofidry]

Findings:

Setup:

# git clone to specific tag
$ composer install --working-dir fixtures/set019-symfony-console
$ COMPOSER_ROOT_VERSION=0.{10,11}.99 composer install
$ composer dump-autoload --classmap-authoritative
$ blackfire run php -dzend.gc_enable=0 bin/php-scoper add-prefix 0114/fixtures/set019-symfony-console --output-dir=build/tmp --force --quiet

Caveats:

• the build is very IO dependent (retrieve config + dumping files)
• GC is enabled
• only one sample is used (more subject to system whims
• the scoped project is a reasonable sized project, i.e. it doesn't have much awfully big files

Results:

commit	wall time	delta	profile	comment
0.11.4	32.9s	N/A	profile	base
6c036d4	39.7s	+7.09%	profile	Fully switch to BetterReflection
b1e3d67	29.1s	-5.25%	profile	Optimize UseStmtCollection
780d40f	26.3s	-15%	profile	Optimize Reflector
ddd6b42	26.3s	-15%	profile	Optimize namespace prefixing
ddd6b42	26.4s	-15%	profile	Remove namespace deep cloning
f4e25d4	23.8s	-22%	profile	Remove use stmt deep cloning