libm: Fix multiple inclusion warning

Conflicts:

	libm/Android.mk

Change-Id: Ifa732ec52fb582c34512cd1d09d918199ae7395e
bionic: update memmove for 32 bits atomic

When src/dst are 32bits aligned, the updated memmove will guarantee
32bits atomic.

Change-Id: I21cb77451270d061b32e3e2d2fda22e7e373b7ff