This patch is an initial attempt to re-structure cgminer source
code from its monolithic design (with nearly all code being
concentrated in main.c) to a more modular one.
In this first stage, the conditionally compiled functions for
GPU and CPU mining were extracted into dedicated files:
* device-cpu.h and device-cpu.c covering WANT_CPUMINE functions
* device-gpu.h and device-gpu.c covering HAVE_OPENCL functions
The main.c file is left untouched as reference, while the
remainder without the extracted parts is located in cgminer.c.
The Makefile.am has been updated to use the re-structured
source files for the build.
Above pure re-structuring *NO* functional modifications were
made. The sources were tested to compile and run on on a
current Linux system with working CPU and GPU mining
(Bitforce not tested due to loack of hardware).
