Summary:
Somehow clang now chooses slightly different arguments to pass to `ld`
in the invocation that `ndk-build` makes to link:
```
--- clang7 2019-05-28 07:47:19.214949009 -0700
+++ clang8 2019-05-28 07:46:55.095924374 -0700
@@ -1,6 +1,15 @@
"/opt/android_ndk/r15c/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64/lib/gcc/aarch64-linux-android/4.9.x/../../../../aarch64-linux-android/bin/ld"
"--sysroot=/opt/android_ndk/r15c/platforms/android-21/arch-arm64"
+"-EL"
"--fix-cortex-a53-843419"
+"-z"
+"now"
+"-z"
+"relro"
+"-z"
+"max-page-size=4096"
+"--hash-style=gnu"
+"--hash-style=both"
"--no-add-needed"
"--enable-new-dtags"
"--eh-frame-hdr"
@@ -32,7 +41,7 @@
"--fatal-warnings"
"-lc"
"-lm"
-"-lstdc++"
+"-lc++"
"-lm"
"-lgcc"
"-ldl"
```
In particular:
- `lc++` results in `libc++.so` not found from the toolchain
- the forced relocation `-z relro` fails with "/..//bin/ld: ./obj/local/arm64-v8a/objs/hello/__/hello.o: Relocations in generic ELF (EM: 183)" and other weirder errors
Somehow pretending the C++ compiler is `clang` instead of `clang++` stops the insanity.
Also add an Application.mk file to specify some sane defaults.
Also add `V=1` to the `ndk-build` invocation in our tests so that when it fails we have a bit more to work with.
Reviewed By: mbouaziz, martintrojer
Differential Revision: D15518447
fbshipit-source-id: 40203814b