Add Vogar expectations file for tests failing because of missing getrandom().

Add Libcore tests using the `getrandom()` syscall (introduced in Linux
3.17) to a new expectations
file (`art/tools/libcore_no_getrandom_failures.txt`) and add new
option `--no-getrandom` to script `art/tools/run-libcore-tests.sh` to
honor this expectations file.

This option is meant for ART Buildbot devices that have a kernel older
than Linux 3.17, like fugu (Nexus Player) devices, which runs
Linux 3.10.

Test: Rely on the ART Buildbot, once crrev.com/c/1811251 is in.
Bug: 141230711
Change-Id: I8c513da63012c86e81038fd1d3cbb57e8ac3c17c
diff --git a/tools/run-libcore-tests.sh b/tools/run-libcore-tests.sh
index 22f2549..5f49bbe 100755
--- a/tools/run-libcore-tests.sh
+++ b/tools/run-libcore-tests.sh
@@ -131,6 +131,9 @@
 gcstress=false
 debug=false
 
+# Run tests that use the getrandom() syscall? (Requires Linux 3.17+).
+getrandom=true
+
 # Don't use device mode by default.
 device_mode=false
 
@@ -164,6 +167,9 @@
   elif [[ "$1" == "-Xgc:gcstress" ]]; then
     gcstress=true
     shift
+  elif [[ "$1" == "--no-getrandom" ]]; then
+    getrandom=false
+    shift
   elif [[ "$1" == "" ]]; then
     break
   else
@@ -214,6 +220,13 @@
   working_packages+=("libcore.libcore.icu")
 fi
 
+if $getrandom; then :; else
+  # Ignore failures in tests that use the getrandom() syscall (which requires
+  # Linux 3.17+). This is needed on fugu (Nexus Player) devices, where the
+  # kernel is Linux 3.10.
+  expectations="$expectations --expectations art/tools/libcore_no_getrandom_failures.txt"
+fi
+
 # Run the tests using vogar.
 echo "Running tests for the following test packages:"
 echo ${working_packages[@]} | tr " " "\n"