portaudio ext Makefile does not include -lmpg123

[assertivist]

This causes the build to fail for me when using gem install. See my comment on grobie/soundcloud2000 issue 58. Manually adding -lmpg123 to the Makefile and running make again successfully builds portaudio.so.

https://github.com/grobie/soundcloud2000/issues/58#issuecomment-173404505

$ gem install audite -- --with-cppflags=-I/usr/local/include --with-ldflags=-L/usr/local/lib
Building native extensions with: '--with-cppflags=-I/usr/local/include --with-ldflags=-L/usr/local/lib'
This could take a while...
ERROR:  Error installing audite:hal ERROR: Failed to build gem native extension.

/usr/bin/ruby.exe -r ./siteconf20160120-6292-bwquhm.rb extconf.rb --with-cppflags=-I/usr/local/include --with-ldflags=-L/usr/local/lib
checking for portaudio.h... yes
checking for main() in -lportaudio... yes
checking for PaStreamCallbackTimeInfo in portaudio.h... yes
creating Makefile

make "DESTDIR=" clean
rm -f
rm -f portaudio.so  *.o  *.bak mkmf.log .*.time

make "DESTDIR="
gcc -I. -I/usr/include/ruby-2.2.0 -I/usr/include/ruby-2.2.0/ruby/backward -I/usr/include/ruby-2.2.0 -I. -DHAVE_PORTAUDIO_H -DHAVE_TYPE_PASTREAMCALLBACKTIMEINFO -I/usr/local/include  -ggdb -O2 -pipe -Wimplicit-function-declaration    -o portaudio.o -c portaudio.c
portaudio.c: In function ‘rb_portaudio_wait’:
portaudio.c:139:3: warning: implicit declaration of function ‘rb_thread_call_without_gvl’ [-Wimplicit-function-declaration]
   rb_thread_call_without_gvl(portaudio_wait, portaudio, RUBY_UBF_IO, NULL);
   ^
rm -f portaudio.so
gcc -shared -o portaudio.so portaudio.o -L. -L/usr/lib -L/usr/local/lib -Wl,--export-all-symbols -Wl,--enable-auto-image-base,--enable-auto-import    -lruby220 -lportaudio  -lpthread -lgmp -ldl -lcrypt
portaudio.o: In function `rb_portaudio_write_from_mpg':
/home/user/.gem/ruby/gems/audite-0.4.0/ext/portaudio/portaudio.c:120: undefined reference to `mpg123_read'
/home/user/.gem/ruby/gems/audite-0.4.0/ext/portaudio/portaudio.c:120:(.text+0x4f6): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `mpg123_read'
/home/user/.gem/ruby/gems/audite-0.4.0/ext/portaudio/portaudio.c:130: undefined reference to `mpg123_plain_strerror'
/home/user/.gem/ruby/gems/audite-0.4.0/ext/portaudio/portaudio.c:130:(.text+0x51e): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `mpg123_plain_strerror'
collect2: error: ld returned 1 exit status
Makefile:254: recipe for target 'portaudio.so' failed
make: *** [portaudio.so] Error 1

make failed, exit code 2