Add a way to avoid if_nametoindex function for non-posix linux platforms that don't support it

include/grpc/impl/codegen/port_platform.h

@@ -465,6 +465,10 @@ typedef unsigned __int64 uint64_t;
 #define GRPC_ARES 1
 #endif
 
+#ifndef GRPC_IF_NAMETOINDEX
+#define GRPC_IF_NAMETOINDEX 1
+#endif
+
 #ifndef GRPC_MUST_USE_RESULT
 #if defined(__GNUC__) && !defined(__MINGW32__)
 #define GRPC_MUST_USE_RESULT __attribute__((warn_unused_result))

src/core/lib/iomgr/grpc_if_nametoindex_posix.cc

@@ -20,7 +20,7 @@
 
 #include "src/core/lib/iomgr/port.h"
 
-#ifdef GRPC_POSIX_SOCKET
+#if GRPC_IF_NAMETOINDEX == 1 && defined(GRPC_POSIX_SOCKET_IF_NAMETOINDEX)
 
 #include "src/core/lib/iomgr/grpc_if_nametoindex.h"
 
@@ -38,4 +38,5 @@ uint32_t grpc_if_nametoindex(char* name) {
   return out;
 }
 
-#endif /* GRPC_POSIX_SOCKET */
+#endif /* GRPC_IF_NAMETOINDEX == 1 && \
+          defined(GRPC_POSIX_SOCKET_IF_NAMETOINDEX) */

src/core/lib/iomgr/grpc_if_nametoindex_unsupported.cc

@@ -20,7 +20,7 @@
 
 #include "src/core/lib/iomgr/port.h"
 
-#ifndef GRPC_POSIX_SOCKET
+#if GRPC_IF_NAMETOINDEX == 0 || !defined(GRPC_POSIX_SOCKET_IF_NAMETOINDEX)
 
 #include "src/core/lib/iomgr/grpc_if_nametoindex.h"
 
@@ -34,4 +34,5 @@ uint32_t grpc_if_nametoindex(char* name) {
   return 0;
 }
 
-#endif /* GRPC_POSIX_SOCKET */
+#endif /* GRPC_IF_NAMETOINDEX == 0 || \
+          !defined(GRPC_POSIX_SOCKET_IF_NAMETOINDEX) */

src/core/lib/iomgr/port.h

@@ -184,6 +184,7 @@
 #define GRPC_POSIX_SOCKET_EV_EPOLLEX 1
 #define GRPC_POSIX_SOCKET_EV_POLL 1
 #define GRPC_POSIX_SOCKET_EV_EPOLL1 1
+#define GRPC_POSIX_SOCKET_IF_NAMETOINDEX 1
 #define GRPC_POSIX_SOCKET_IOMGR 1
 #define GRPC_POSIX_SOCKET_RESOLVE_ADDRESS 1
 #define GRPC_POSIX_SOCKET_SOCKADDR 1