logger: Add sysfs interface to Enable / Disable Android Logger

- switching done via /sys/kernel/logger_mode interface
default is 0 (off)
Credits to AndiP
lib/int_sqrt.c: optimize square root algorithm
Thanks to https://github.com/jfdsmabalot/kernel_samsung_msm8974ab/commit/c0733d6ddc224481fbf06c43b93afe5b5d8bbcd9
lib/memcopy: use glibc version
Thanks to https://github.com/jfdsmabalot/kernel_samsung_msm8974ab/commit/95a2116225dadb075eb4fc862618eae46a89b427
fs: namespace: Fix uninitialized warning
net/ipv4: Enable additional TCP cong algorithms
arch/arm/configs: Enable advanced congestion-avoidance algorithms
Revert "lib/memcopy: use glibc version"

This reverts commit 02fa10a7485b4e63071983379ed6b5a58a434ab0.
firmware/synaptics: Don't check if generated files are present, just remove always

Conflicts:
	firmware/Makefile
Makefile: Enhance graphite flags

Conflicts:
	Makefile