Switch the preprocessor over to using the hash table library. On my
system, this improves the runtime of the output of test/pref/macro.pl
from over 600 seconds to 7 seconds.
Macros have an odd mix of case-sensitive and case-insensitive
behaviour, plus there are matching parameters for arguments, etc. As
a result, we use case-insensitive hash tables and use a linked list to
store all the possible isomorphs.
Use the new hash table function library to store labels. When
compiling on my 64-bit system, it reduces the assembly time for the
output of test/perf/label.pl from 73 to 7 seconds.
