Make a basic toplevel Makefile.
Make a basic toplevel Makefile.

This is so others not using Debian can use this library as well.

yxl/opencore-amr-js,Distrotech/opencore-amr,yxl/opencore-amr-js,jiangjianping/opencore-amr,yxl/opencore-amr-js,BelledonneCommunications/opencore-amr,jiangjianping/opencore-amr,yxl/opencore-amr-js,KurentoLegacy/opencore-amr,VFR-maniac/opencore-amr,KurentoLegacy/opencore-amr,Distrotech/opencore-amr,yxl/opencore-amr-js,BelledonneCommunications/opencore-amr,KurentoLegacy/opencore-amr,lyx2014/-opencore-amr,lyx2014/-opencore-amr,VFR-maniac/opencore-amr,Distrotech/opencore-amr,VFR-maniac/opencore-amr