Speed up Cython compilation process on Linux (cef_logging.cpp)

[cztomczak]

Currently in cython_setup.py there are -flto, -fdata-sections, -ffunction-sections flags being set that slow down compilation process siginifcantly:

if FAST_FLAG:
            extra_compile_args.extend(["-flto",
                                       "-std=gnu++11"])
            extra_link_args.extend(["-flto"])
        else:
            # Fix "ImportError ... undefined symbol ..." caused by CEF's
            # include/base/ headers by adding the -flto flag (Issue #230).
            # Unfortunately -flto prolongs compilation time significantly.
            # More on the other flags: https://stackoverflow.com/questions/
            # 6687630/ .
            extra_compile_args.extend(["-flto",
                                       "-fdata-sections",
                                       "-ffunction-sections",
                                       "-std=gnu++11"])
            extra_link_args.extend(["-flto",
                                    "-Wl,--gc-sections"])

Adding these flags was required due to undefined symbols in caused by "cef_logging.h" (include/base/). However I think this may be fixed by creating "cef_logging.cpp" which should include "cef_logging.h" and the compiled object should be included during linking.