Add NO_ATOMIC_INLINES check, to be used by libcutils

In Clang, extern always_inline symbols are exported, causing clashes
when linking something that includes the function definitions in
several source files (e.g. libcutils).
We need an option to make sure they're included only once.

Change-Id: I50279557fb3a02c633ce6428c3db79aa448c8b38
Signed-off-by: Bernhard Rosenkränzer <Bernhard.Rosenkranzer@linaro.org>