Change LANGUAGE C into lower-case, fixes http://stackoverflow.com/questions/12514664/postgresql-procedural-language-c-not-found
define int4 to be short, following http://forums.codeguru.com/showthread.php?257362-how-to-define-a-INT4-type%28int-that-occupy-4-bytes%29
Merge pull request #2 from sneumann/master

minor tweaks to compile on Ubuntu12.04 with gcc-4.6.3 into PostgreSQL 9.3