any idea why scons is hanging here while trying to compile csound5?

C S O U N D   5

SCons build file for Csound 5:
API library, plugin opcodes, utilities, and front ends.

By Michael Gogins 

For custom options, run 'scons -h'.
For default options, run 'scons -H'.
If headers or libraries are not found, edit 'custom.py'.
For Linux, run in the standard shell
    with standard Python and just run 'scons'.
For MinGW, run in the MSys shell
    and use www.python.org WIN32 Python to run scons.
For Cygwin, run in the Cygwin shell
    and use Cygwin Python to run 'scons'.

System platform is 'darwin'.
Build platform is 'darwin'.
SCons tools on this platform:  ['default', 'gnulink', 'gcc', 'g++', 'g77',
'gas', 'ar', 'CVS', 'jar', 'javac', 'javah', 'lex', 'm4', 'RCS', 'rmic',
'tar', 'yacc', 'zip']

Using single-precision floating point for audio samples.
Checking for C header file sndfile.h... yes
Checking for C header file portaudio.h... no
Checking for C++ header file FL/Fl.H... no
Checking for C++ header file boost/any.hpp... no
Checking for C header file io.h... no
Checking for C header file fcntl.h... yes
Checking for C header file unistd.h... yes
Checking for C header file malloc.h... no
Checking for C header file sgtty.h... yes
Checking for C header file os.h... no
Checking for C header file sys/ioctl.h... yes
Checking for C header file sys/time.h... yes
Checking for C header file sys/types.h... yes
Checking for C header file term/ios.h... no
Checking for C header file termios.h... yes
Checking for C header file string.h... yes
Checking for C header file strings.h... yes
Checking for C header file dirent.h... yes
Checking for C function itoa()... no
sh: line 1: fltk-config: command not found
sh: line 1: fltk-config: command not found
Checking for C header file fluidsynth.h... no
Calling makedb
scons: done reading SConscript files.
scons: Building targets ...
./makedb strings/all_strings American