Compiles fine on my mac:

vivi ~/src/posixlock-0.0.1 % ruby extconf.rb
creating Makefile
vivi ~/src/posixlock-0.0.1 % make
gcc -fno-common   -g -Os -pipe -no-cpp-precomp -fno-common 
-DHAVE_INTTYPES_H   -pipe -pipe  -I. 
-I/usr/lib/ruby/1.6/powerpc-darwin7.0 -I.    -c -o posixlock.o posixlock.c
cc -fno-common   -g -Os -pipe -no-cpp-precomp -fno-common 
-DHAVE_INTTYPES_H   -pipe -pipe  -dynamic -bundle -undefined suppress 
-flat_namespace  -L/usr/lib/ruby/1.6/powerpc-darwin7.0 -L/usr/lib  -o 
posixlock.bundle posixlock.o   -ldl -lobjc
vivi ~/src/posixlock-0.0.1 % sudo make install
posixlock.bundle -> /usr/lib/ruby/1.6/powerpc-darwin7.0/posixlock.bundle
chmod 0755 /usr/lib/ruby/1.6/powerpc-darwin7.0/posixlock.bundle
vivi ~/src/posixlock-0.0.1 %

How should I test it?

-- 
Rando Christensen
<eyez / illuzionz.org>