Deoptimize zygote compiled methods in DeoptimizeBootImage.

Those methods don't get compiled with the "debuggable" flag,
so we need to deoptimize them.

Also fix a bug revealed by the new test where a concurrent
JIT collection happens when trying to disable it.

Also make DeoptimizeBootImage truly mutator lock exclusive.

Test: 689-zygote-jit-deopt
Change-Id: I00607dbe100350c5328293c35c87946fa97924b8
diff --git a/test/689-zygote-jit-deopt/info.txt b/test/689-zygote-jit-deopt/info.txt
new file mode 100644
index 0000000..100032e
--- /dev/null
+++ b/test/689-zygote-jit-deopt/info.txt
@@ -0,0 +1,2 @@
+Regression test for debuggable apps that need to deoptimize
+methods JIT-compiled by the zygote.