Major compiler changes

- Remove CC wrapper; deprecated
- CFLAGS adjusted; for better stability, faster speed
- LDFLAGS adjusted; strip down modules
- Remove -w flag; -Werror-implicit-function-declaration is crucial for a stable kernel
- Add arter97's custom CFLAGS; -s for smaller kernel, -pipe for faster compilation, -Ofast for kernel's ultimate fast speed, and some others that Linaro recommends
- Enable hard-float