Compile problem with gd-2.0.28

[Cliff Addy]

Trying to compile gd-2.0.28 under 4.9-RELEASE.  I get the error

   ./.libs/libgd.so: undefined reference to `pthread_mutex_unlock'
   ./.libs/libgd.so: undefined reference to `pthread_mutex_destroy'
   ./.libs/libgd.so: undefined reference to `pthread_mutex_lock'
   ./.libs/libgd.so: undefined reference to `pthread_mutex_init'

Looks to me like a bad reference to a threads library.

Any ideas ... ?

Cliff