build/make/Android.mk: support TARGET_ARCH_ABI=x86_64

requires r10e or newer:

Android NDK, Revision 10e (May 2015)
...
Other bug fixes:
...
  - Fixed .asm support for ABI x86_64.

Change-Id: I51ec9a5f77c982b7412d922e896348a83ae2d7d6

configure

diff --git a/configure b/configure
index 6cac15a..fcab145 100755
--- a/configure
+++ b/configure
@@ -132,6 +132,7 @@
 all_platforms="${all_platforms} x86-win32-vs10"
 all_platforms="${all_platforms} x86-win32-vs11"
 all_platforms="${all_platforms} x86-win32-vs12"
+all_platforms="${all_platforms} x86_64-android-gcc"
 all_platforms="${all_platforms} x86_64-darwin9-gcc"
 all_platforms="${all_platforms} x86_64-darwin10-gcc"
 all_platforms="${all_platforms} x86_64-darwin11-gcc"