Added tests for bug detection on locals

tests_lit/asan_tests/errorlocaloffbynegative.ll

+; Make sure off-by-negative OOB accesses of locals are caught
+
+; REQUIRES: no_minimal_build
+
+; RUN: llvm-as %s -o - | pnacl-freeze > %t.pexe && %S/../../pydir/szbuild.py \
+; RUN:     --fsanitize-address --sz="-allow-externally-defined-symbols" \
+; RUN:     %t.pexe -o %t && not --crash %t 2>&1 | FileCheck \
+; RUN:     --check-prefix=CHECK32 %s
+
+declare external void @exit(i32)
+
+; A global array
+@arr = internal constant [12 x i8] zeroinitializer
+
+define i32 @access() {
+  %arr = alloca i8, i32 12, align 1
+  %arraddr = ptrtoint i8* %arr to i32
+  %badaddr = add i32 -4, %arraddr
+  %badptr = inttoptr i32 %badaddr to i32*
+  %result = load i32, i32* %badptr, align 1
+  ret i32 %result
+}
+
+define void @_start(i32 %__0) {
+  %result = call i32 @access()
+  call void @exit(i32 0)
+  unreachable
+}
+
+; CHECK32: Illegal access of 4 bytes at
+