do not merge. Move property setting from libcutils to bionic.

do not merge. Move property setting from libcutils to bionic.

Backport I110b653a58f3

All the other property stuff is already here.  Property setting was
only in libcutils previously to leverage a utility function / constant
or two.

Unfortunately in the process of fixing a race condition we would've
had to do break abstraction boundaries and put some libc-internal
details into libcutils so instead of that we'll just move this
into bionic.

Along with Iee1ca9b7, this now passes:

$ adb shell am instrument -w -e class android.os.SystemPropertiesTest \
  com.android.frameworks.coretests.systemproperties/android.test.InstrumentationTestRunner

  Bug: 3511230

Change-Id: I1b588db3344169621e1279ecc0b660cf4e1015d7