Nothing within the library actually uses these defines for anything
any more.
If necessary, the built-in defines __APPLE__ and __linux__ can be
used instead of these manually added defines. This is similar to how
we use _WIN32 instead of manually defining WIN32.
Treating warnings as error is useless if no warning is activated.
Several build systems enable -Wall in the CLFAGS, which in combination
with -Werror can trigger undesired build errors.
This avoids coupling the architecture directly to the platform,
allowing building on e.g. linux on architectures other than x86,
without having to explicitly specify USE_ASM=No while building
on those.
Later this will also facilitate enabling assembly optimizations
where applicable, e.g. arm assembly on linux.
This is enabled for platforms/compilers that support the -MMD
option, which creates a dependency file named out.d when compiling
to a file named out.o, only including local, not system headers.
The additional -MP option adds phony targets for all included
headers, to avoid having make error out due to "no rule to make
target foo.h" if a header is renamed/removed.
This makes sure that all the right files are rebuilt if a header
is changed, avoiding the need for a full rebuild if only a few
files are affected.
Don't enable threading globally since the MSVC/ARM build target
(neither windows phone nor windows rt) doesn't support the normal
windows threading functions.
