If the configure script complains about a missing library but you are sure
the library (including developer support) is installed, make sure to have
the CFLAGS and LDFLAGS variables set up properly.
On Unix/Linux systems you may want to use
  CFLAGS="-I/usr/local/include"
  LDFLAGS="-L/usr/local/lib"
  export CFLAGS
  export LDFLAGS
On Mac OS you may want to use
  CFLAGS="-I/sw/include"
  LDFLAGS="-L/sw/lib"
  export CFLAGS
  export LDFLAGS
if you have Fink installed.