Add build system support for LOCAL_DETECT_INTEGER_OVERFLOWS. When enabled,
an attempt to perform an integer arithmetic operation which overflows
will result in a call to abort(). This is intended for security
sensitive code, where integer overflow operations are not expected
nor desirable.

Two classes of underflows/overflows are detected and blocked:

1) Signed integer underflow/overflow.
2) Unsigned integer underflow/overflows.

Signed integer overflows are undefined behavior, according to the
C standard. Unsigned integer overflows are defined behavior, but
still undesirable in security sensitive code.

Only clang is supported today. gcc has -ftrapv for handling signed
integer overflow, but it's widely considered broken
( and we're
deliberately avoiding it's use here.

Change-Id: Ib4918dc84e37e83d4205e5035544545d91671e5f
Vaguely-Related-Bug: 11859726
2 files changed