Makefile: Add pipe flag to KBUILD

Signed-off-by: Zhao Wei Liew <zhaoweiliew@gmail.com>
Makefile: Perform vectorization on trees for KBUILD

Signed-off-by: Zhao Wei Liew <zhaoweiliew@gmail.com>
Makefile: Compile linker with -Ofast

Signed-off-by: Zhao Wei Liew <zhaoweiliew@gmail.com>