Workaround broken gnumake realpath on Windows.

Also, added missing build scripts for flatc on Windows and fixed
numerous issues in the flatbuffers/android/jni/include.mk makefile.

Tested:
Verified dependent project (motive) can generate flatbuffers headers
with these changes on Android.

Bug: 25780616

Change-Id: I73f0dec8f7a6a7eb4e71951a8f1cd3e0d343a9ff

android/jni/run_flatc.py

@@ -0,0 +1,46 @@
+#!/usr/bin/python
+# Copyright 2015 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+import platform
+import subprocess
+import sys
+
+EXECUTABLE_EXTENSION = '.exe' if platform.system() == 'Windows' else ''
+# Paths to search for flatc relative to the current working directory.
+FLATC_SEARCH_PATHS = [os.path.curdir, 'Release', 'Debug']
+
+def main():
+  """Script that finds and runs flatc built from source."""
+  if len(sys.argv) < 2:
+    sys.stderr.write('Usage: run_flatc.py flatbuffers_dir [flatc_args]\n')
+    return 1
+  cwd = os.getcwd()
+  flatc = ''
+  flatbuffers_dir = sys.argv[1]
+  for path in FLATC_SEARCH_PATHS:
+    current = os.path.join(flatbuffers_dir, path,
+                           'flatc' + EXECUTABLE_EXTENSION)
+    if os.path.exists(current):
+      flatc = current
+      break
+  if not flatc:
+    sys.stderr.write('flatc not found\n')
+    return 1
+  command = [flatc] + sys.argv[2:]
+  return subprocess.call(command)
+
+if __name__ == '__main__':
+  sys.exit(main())