lang/ruby18-base doesn't build on DragonFlyBSD

[Thomas Schlesinger <schlesinger%netcologne.de@localhost>]

Hi,

when I do a bmake install for  lang/ruby18-base, I get this error. I'm using 
DragonFlyBSD 1.7.0-DEVELOPMENT.

[..]
cc -O2 -I/usr/include  -fPIC  -DRUBY_EXPORT -I. -I. -I/usr/include -c dmyext.c
ar rcu libruby18-static.a array.o  bignum.o  class.o  compar.o  dir.o  dln.o  
enum.o  error.o  eval.o  file.o  gc.o  hash.o  inits.o  io.o  marshal.o  
math.o  numeric.o  object.o  pack.o  parse.o  process.o  prec.o  random.o  
range.o  re.o  regex.o  ruby.o  signal.o  sprintf.o  st.o  string.o  struct.o  
time.o  util.o  variable.o  version.o  isnan.o isinf.o dmyext.o
cc -O2 -I/usr/include  -fPIC  -DRUBY_EXPORT -I. -I. -I/usr/include -c main.c
cc main.o  libruby18-static.a -lcrypt -lm   -o 
miniruby -O2 -I/usr/include  -fPIC  -DRUBY_EXPORT -L/usr/lib -Wl,-R/usr/lib 
-Wl,-R/usr/pkg/lib -rdynamic
libruby18-static.a(eval.o)(.text+0x14bda): In function `rb_thread_start_0':
: undefined reference to `pthread_create'
*** Error code 1

Stop.
bmake: stopped in /usr/pkgsrc/lang/ruby18-base/work/ruby-1.8.5
*** Error code 1
[..]

Thomas