Remove jdwpspy.

Change-Id: Ic9814dadcf1ccf46e280bddde0dffbef8438e48d
Bionic has <sys/ucontext.h> now.

Change-Id: I7b97df04204b22e8976b64bf93af72a311ddb0e9
Add property to disable sampling profiler.

This is to enable power measurements to be performed without
the profiler running.  The default is off (no profiler).

To enable the profiler:

adb shell setprop dalvik.vm.profiler 1

Change-Id: I983f2ffcf6c2c7bb8e29f0610fe259f3d56a4b1d

Conflicts:
	runtime/profiler.cc