stdioext: port to newer 32-bit Android

Problem reported by Tom Yan in:
https://lists.gnu.org/archive/html/bug-gnulib/2018-07/msg00014.html
* lib/stdio-impl.h (_gl_FILE_flags_t) [__ANDROID__]: New macro.
(fp_) [__ANDROID__]: Use it.

Author: eggert

ChangeLog

@@ -1,3 +1,11 @@
+2018-12-22  Paul Eggert  <eggert@cs.ucla.edu>
+
+	stdioext: port to newer 32-bit Android
+	Problem reported by Tom Yan in:
+	https://lists.gnu.org/archive/html/bug-gnulib/2018-07/msg00014.html
+	* lib/stdio-impl.h (_gl_FILE_flags_t) [__ANDROID__]: New macro.
+	(fp_) [__ANDROID__]: Use it.
+
 2019-01-04  Bruno Haible  <bruno@clisp.org>
 
 	lock: Fix link error with --enable-threads=pth.

lib/stdio-impl.h

@@ -61,6 +61,11 @@
 #  define _r pub._r
 #  define _w pub._w
 # elif defined __ANDROID__ /* Android */
+#  ifdef __LP64__
+#   define _gl_flags_file_t int
+#  else
+#   define _gl_flags_file_t short
+#  endif
   /* Up to this commit from 2015-10-12
      <https://android.googlesource.com/platform/bionic.git/+/f0141dfab10a4b332769d52fa76631a64741297a>
      the innards of FILE were public, and fp_ub could be defined like for OpenBSD,
@@ -70,8 +75,8 @@
 #  define fp_ ((struct { unsigned char *_p; \
                          int _r; \
                          int _w; \
-                         int _flags; \
-                         int _file; \
+                         _gl_flags_file_t _flags; \
+                         _gl_flags_file_t _file; \
                          struct { unsigned char *_base; size_t _size; } _bf; \
                          int _lbfsize; \
                          void *_cookie; \