Support getting/setting API level in static binaries.

Bug: http://b/27917272
Test: fixes static semaphore.sem_wait_no_EINTR_in_sdk_less_equal_than_23 test
Change-Id: Ifeeff20772ff0308aab9417d48671b604a3e9665
diff --git a/libdl/Android.bp b/libdl/Android.bp
index 082cdea..d5fae0e 100644
--- a/libdl/Android.bp
+++ b/libdl/Android.bp
@@ -74,7 +74,7 @@
         whole_static_libs: ["libdl_static"],
     },
     static: {
-        srcs: ["libdl_static.c"],
+        srcs: ["libdl_static.cpp"],
     },
     cflags: [
         "-Wall",