Change hard-coded temporary directory.

The properties tests creates a temporary directory in /data/nativetest,
but this directory might not exist in all circumstances.
Change this to create the temporary directory in /data/local/tmp.

Change-Id: I812d3e24fcd084c5d74055c9faa95b1656f255bc

Conflicts:
	tests/property_benchmark.cpp
	tests/system_properties_test.cpp

Conflicts:
	tests/system_properties_test.cpp
Fix abort(3) to raise SIGABRT rather than causing SIGSEGV.

tgkill() needs the .save stack unwinding directive to get the complete
stack trace.

BUG: https://code.google.com/p/android/issues/detail?id=16672

Change-Id: Ifb447dca2147a592c48baf32769dfc175d8aea72

Conflicts:
	libc/unistd/abort.c