Switched to CMake. CMake compiles faster.

Added libsyn123 library as it's needed since version 1.26.

Before:

time make package/mpg123/compile -j 12
Executed in   16.05 secs   fish           external
   usr time   26.65 secs    0.00 micros   26.65 secs
   sys time    4.82 secs  833.00 micros    4.81 secs

After:

time make package/mpg123/compile -j 12
Executed in   12.12 secs   fish           external
   usr time   19.35 secs    0.00 micros   19.35 secs
   sys time    3.22 secs  752.00 micros    3.22 secs

Signed-off-by: Rosen Penev <rosenp@gmail.com>