Stricter signatures to match the new bionic/libc/netbsd/resolv ones.

Change-Id: I690858b85303addc030540bce8512ec9a1e18b4a
diff --git a/ResolverController.cpp b/ResolverController.cpp
index 13dd930..07fa6cf 100644
--- a/ResolverController.cpp
+++ b/ResolverController.cpp
@@ -38,7 +38,7 @@
 }
 
 int ResolverController::setInterfaceDnsServers(const char* iface, const char* domains,
-        char** servers, int numservers) {
+        const char** servers, int numservers) {
     if (DBG) {
         ALOGD("setInterfaceDnsServers iface = %s\n", iface);
     }