Hide most symbols in libmemunreachable

In preparation for making libmemunreachble vendor_available, hide
everything but the public ABI using a version script.  The unit
tests now have to compile statically against libmemunreachable,
so split out the tests that run against the public API into a
separate test.

Bug: 132302484
Test: atest memunreachable_test memunreachable_unit_test
Change-Id: Ie9dec073fdeee342776566abedd50f7498476eca
diff --git a/libmemunreachable.map b/libmemunreachable.map
new file mode 100644
index 0000000..0d0d954
--- /dev/null
+++ b/libmemunreachable.map
@@ -0,0 +1,13 @@
+LIBMEMUNREACHABLE {
+  global:
+    LogUnreachableMemory;
+    NoLeaks;
+    extern "C++" {
+      android::GetUnreachableMemory*;
+      android::GetUnreachableMemoryString*;
+      android::Leak::*;
+      android::UnreachableMemoryInfo::*;
+    };
+  local:
+    *;
+};