Fix build for x86. Remove duplicate mcmchr from Android.mk. Other implemented in arch-x86/x86.mk

Change-Id: I90a562960b214dd02b015d3e2715f711907ae9e8
Fix pointer type error from _Unwind_Ptr being redefined

Change-Id: I51acde47876fac566055d763c8d7ca75f1fad105