Revert "build: Add more cflags to the Makefile"

This reverts commit 4c6e7e086a3541f8d7db77cd6023856b782b33d5.
Fix compiler warnings for VS2010 /W4 in bitstream.c and cabac.c.

- Working towards issue #11.
Fix compiler warnings for VS2010 /W4 in config.c and encmain.c.

- Working towards issue #11.
- Widened datatypes for cfg struct members that take values from atoi to full
  ints so that bounds checking can be done after parsing without overflow.
Fixed SAO cost checking, disabling SAO when RD-cost is 0

Decreases overall BD-rate a bit more, this fix prevents coding zero offsets to the bitstream
Fix for SAO band offset merge cost calculation.

Gives a tiny improvement to both bit rate and psnr.
encoder: Export g_convert_to_bit correctly

It is a global table initialized in encoder.c and used all over the
codebase.