Clogger 0.4.0 - small cleanups

Clogger is Rack middleware for logging HTTP requests. The log format
is customizable so you can specify exactly which fields to log.

Changes:

Small cleanups and minor enhancements (mainly for the optional
C extension) for this release:

Eric W. (10):
ext: use FIX macros instead of generic NUM macros if possible
ext: preserve subclasses of Rack::Utils::HeaderHash
test: fix Linux memory usage test
avoid direct require of “rack” to quiet warnings
ext: GC safety fix when throwing an exception
ext: eliminate unused variable
ext: fix signedness and shadow warnings
ext: sparse cleanups
ext: avoid void pointer arithmetic
clogger 0.4.0