Have the sanitizers trap rather than abort.

abort() seems friendlier, but in practice it puts a couple of irrelevant
libc.so frames on the top of the stack trace and clobbers all the
registers that might have helped remotely debug a sanitizer failure.
Let's switch to trapping directly in the sanitized code instead.

Bug: http://b/298741930
Test: treehugger
Change-Id: I4fca63cb42bfba16a934c1fa88b08697faf3be41