use __BIONIC__ not __ANDROID__

This is more correct since this is a feature of the C library in use,
and not actually Android specific.

This matches version of patch that went upstream:
  http://git.netfilter.org/iptables/commit/?id=9dd0c484767c9fa3852b23c790d3d5e84e510beb

Test: builds
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Iec8088a51b471a8b10a28c0ac8c4badf60bbbe5f
diff --git a/libiptc/libip4tc.c b/libiptc/libip4tc.c
index 0814705..78a896f 100644
--- a/libiptc/libip4tc.c
+++ b/libiptc/libip4tc.c
@@ -22,7 +22,7 @@
 #define inline
 #endif
 
-#if !defined(__ANDROID__) && (!defined(__GLIBC__) || (__GLIBC__ < 2))
+#if !defined(__BIONIC__) && (!defined(__GLIBC__) || (__GLIBC__ < 2))
 typedef unsigned int socklen_t;
 #endif
 
diff --git a/libiptc/libip6tc.c b/libiptc/libip6tc.c
index 91676c4..06cd623 100644
--- a/libiptc/libip6tc.c
+++ b/libiptc/libip6tc.c
@@ -23,7 +23,7 @@
 #define inline
 #endif
 
-#if !defined(__ANDROID__) && (!defined(__GLIBC__) || (__GLIBC__ < 2))
+#if !defined(__BIONIC__) && (!defined(__GLIBC__) || (__GLIBC__ < 2))
 typedef unsigned int socklen_t;
 #endif