[ndk] Change ndk deps in src and relocate to third_party/boringssl

Because the android sdk managed by CIPD (see go/use-adjective-apis),
its deps repo ndk needs to be relocated, as well as hooked by the root
DEPS instead of recursedeps. This CL addes android ndk deps in
util/bot/DEPS.

Bug: chromium:659808
Change-Id: I270053ae56ba1caaf9c67f2240855eafd499b782
Reviewed-on: https://boringssl-review.googlesource.com/24864
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

.gitignore

@@ -5,6 +5,7 @@ ssl/test/runner/runner
 doc/*.html
 doc/doc.css
 
+util/bot/android_ndk
 util/bot/android_tools
 util/bot/cmake-linux64
 util/bot/cmake-linux64.tar.gz

util/bot/DEPS

@@ -21,7 +21,12 @@ vars = {
 }
 
 deps = {
-  'boringssl/util/bot/android_tools': {
+  'boringssl/util/bot/android_ndk': {
+    'url': Var('chromium_git') + '/android_ndk.git' + '@' + 'e951c37287c7d8cd915bf8d4149fd4a06d808b55',
+    'condition': 'checkout_android',
+  },
+
+'boringssl/util/bot/android_tools': {
     'url': Var('chromium_git') + '/android_tools.git' + '@' + 'c9f9bbf0a6c862fbef6115e80e8617093cd58e6b',
     'condition': 'checkout_android',
   },