libm: These optimizations are only for Krait

 * Issues on other chipsets. Resync with CAF and only use on specific
   chipsets (Krait, Sparrow).

Change-Id: I6a11f3f8e3250359259edf5f57e0d9e7068c5375
Merge branch 'cm-10.1' of https://github.com/CyanogenMod/android_bionic into DJL10.1