libm: Add a proper sincos() implementation

Add a proper sincos() implementation that unifies the common
calculations for sin and cos instead of running them twice.

This should cause a speedup even in code not using that
(fairly uncommon) function because gcc can optimize separate
sin() and cos() calls into sincos() calls.

Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>
bionic: Add ARMv7 optimized string handling routines

Add ARMv7 - and especially Cortex-A9 - optimized string handling
routines based on the versions found in the cortex-strings library.

Change-Id: I497075bea5b82aef8989625bdec512029676fe7f
Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>
bionic: Add workarounds for current compilers

With current compilers, we're getting "this function cannot be inlined"
errors on vsnprintf and strlcpy because the always_inline attribute is
set.

Before marking this a "fix" instead of a "workaround", we should figure
out why the functions can't be inlined.

Change-Id: Id6c5464defafb3f9044c102d32a57e70d760b05d
Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>