Instead of never overwriting compiler-gcc.h if it exists, overwrite it
by default except if OVERWRITE_GCCH=0 is set in the environment.
Most kernels *do* need this file replaced and won't build without this
patch.
The 5.0 kernel now includes -Werror= parameters in the makefile, this
changes downstreamkernel_prepare.sh to support them. Without this, the
script will replace, for example, -Werror=blah with =blah, which causes
the kernel compilation to fail.
We used to put a "compiler-gcc6.h" file inside every vendor kernel's
aport. This is redundant and only works with GCC6. With this patch,
a common "compiler-gcc.h" file will be used, that works independently
of the GCC version.
The file is from Decatf's android_kernel_samsung_p4 repository, where
it was taken from upstream Linux, but adjusted to work with older
vendor kernels (different #ifndef check at the top etc).
bd0772df21/include/linux/compiler-gcc.h
