Switch bionic-unit-tests to libc++_static.

Bug: http://b/27549327
Test: run bionic-unit-tests, bionic-unit-tests-glibc.
Change-Id: I719899624dec83728a3d5b8169079e5c91c63c04
diff --git a/tests/Android.bp b/tests/Android.bp
index 84be7bc..fe34b9f 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -366,6 +366,8 @@
 
     include_dirs: ["bionic/libc"],
 
+    stl: "libc++_static",
+
     target: {
         android: {
             shared_libs: [
diff --git a/tests/Android.build.mk b/tests/Android.build.mk
index 9236558..266c7d7 100644
--- a/tests/Android.build.mk
+++ b/tests/Android.build.mk
@@ -102,11 +102,7 @@
     $($(module)_ldlibs) \
     $($(module)_ldlibs_$(build_type)) \
 
-ifeq ($(LOCAL_FORCE_STATIC_EXECUTABLE),true)
-  LOCAL_CXX_STL := libc++_static
-else
-  LOCAL_CXX_STL := libc++
-endif
+LOCAL_CXX_STL := libc++_static
 
 ifeq ($(build_type),target)
   include $(BUILD_$(build_target))
diff --git a/tests/libs/Android.bp b/tests/libs/Android.bp
index 4cd991a..004f668 100644
--- a/tests/libs/Android.bp
+++ b/tests/libs/Android.bp
@@ -26,6 +26,7 @@
     sanitize: {
         never: true,
     },
+    stl: "libc++_static",
     target: {
         darwin: {
             enabled: false,