Add a netcontext variant of gethostbyaddr

Bug: 34953048
Test: Integration tests pass
Change-Id: Id04830345be56cd7a077981c6e2acfb5568e7a88
diff --git a/libc/libc.x86.map b/libc/libc.x86.map
index 8ba5e69..dd2ecca 100644
--- a/libc/libc.x86.map
+++ b/libc/libc.x86.map
@@ -1336,6 +1336,7 @@
     android_getaddrinfofornet;
     android_getaddrinfofornetcontext;
     android_gethostbyaddrfornet;
+    android_gethostbyaddrfornetcontext;
     android_gethostbynamefornet;
     arc4random_addrandom; # arm x86 mips
     arc4random_stir; # arm x86 mips