Merge libdexfile_external into libdexfile (reland 2).

To reduce the number of DSO's. libdexfile_external only adds a few
small functions on top of libdexfile, and it's still only those
functions that are available in the APEX stubs.

Also rename libdexfile_external_static to libdexfile_static, for
consistency.

Since libdexfile now has stubs, we need to add test_for properties to
avoid linking against the stubs in tests.

This relands https://r.android.com/1666119 that got submitted out of
order from https://r.android.com/1664026 - prerequisite changes now
submitted with https://r.android.com/1671709.

Test: Flash and boot with userdebug and eng to try both release and
  debug modules.
Test: art/tools/buildbot-build.sh {--target,--host}
Test: art/build/apex/runtests.sh
Test: mmm art
Bug: 143978909
Change-Id: I6de99052d6d8a9d01d748baabbbcecfe1f4509dc
diff --git a/libdexfile/external/dex_file_ext.cc b/libdexfile/external/dex_file_ext.cc
index 4432f6a..302e188 100644
--- a/libdexfile/external/dex_file_ext.cc
+++ b/libdexfile/external/dex_file_ext.cc
@@ -18,7 +18,6 @@
 
 #include <inttypes.h>
 #include <stdint.h>
-#include <sys/mman.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ -43,6 +42,7 @@
 #include <dex/dex_file_loader.h>
 
 extern "C" {
+
 // Wraps DexFile to add the caching needed by the external interface. This is
 // what gets passed over as ExtDexFile*.
 struct ExtDexFile {