if parameter -D could not be accessed, issue warning and process single file

original author & commit: http://review.android.git.linaro.org/#change,3376

Change-Id: Ibe1bc9d78333ed8e381477034523ce8beec16af7
Merge "if parameter -D could not be accessed, issue warning and process single file" into jb42
Fix -Xjitthreshold (for real this time).

My previous "fix" (c89d83e1c05979b68037ad15413fa4460a88e36f) had the
conditions reversed, so you _had_ to use -Xjitthreshold to get a non-zero
threshold, but when you did, you'd get the default instead of what you
asked for!

This was spotted by the jank tests.

Bug: 8285558
Bug: https://code.google.com/p/android/issues/detail?id=52017
Change-Id: I28270f2573d46929eb10d30789fecf7d5a8cea75