Fix error: ‘NI_MAXSERV’ undeclared

[widgetii]

When I compile libre using arm-linux-musleabi-gcc cross-compiler with musl library I encountered a compilation issue:

[ 59%] Building C object CMakeFiles/re-objs.dir/src/tcp/tcp.c.o
.../git/re/src/tcp/tcp.c: In function ‘tcp_sock_bind’:
.../git/re/src/tcp/tcp.c:725:12: error: ‘NI_MAXSERV’ undeclared (first use in this function)
  char serv[NI_MAXSERV] = "0";
            ^~~~~~~~~~
.../git/re/src/tcp/tcp.c:725:12: note: each undeclared identifier is reported only once for each function it appears in
.../git/re/src/tcp/tcp.c:725:7: warning: unused variable ‘serv’ [-Wunused-variable]
  char serv[NI_MAXSERV] = "0";
       ^~~~
.../re/src/tcp/tcp.c: In function ‘tcp_conn_alloc’:
.../re/src/tcp/tcp.c:886:12: error: ‘NI_MAXSERV’ undeclared (first use in this function)
  char serv[NI_MAXSERV] = "0";
            ^~~~~~~~~~
.../re/src/tcp/tcp.c:886:7: warning: unused variable ‘serv’ [-Wunused-variable]
  char serv[NI_MAXSERV] = "0";
       ^~~~
.../re/src/tcp/tcp.c: In function ‘tcp_conn_bind’:
.../re/src/tcp/tcp.c:963:12: error: ‘NI_MAXSERV’ undeclared (first use in this function)
  char serv[NI_MAXSERV] = "0";
            ^~~~~~~~~~
.../re/src/tcp/tcp.c:963:7: warning: unused variable ‘serv’ [-Wunused-variable]
  char serv[NI_MAXSERV] = "0";
       ^~~~
.../re/src/tcp/tcp.c: In function ‘tcp_conn_connect’:
.../re/src/tcp/tcp.c:1037:12: error: ‘NI_MAXSERV’ undeclared (first use in this function)
  char serv[NI_MAXSERV];
            ^~~~~~~~~~
.../re/src/tcp/tcp.c:1037:7: warning: unused variable ‘serv’ [-Wunused-variable]
  char serv[NI_MAXSERV];
       ^~~~

It turns out the same issue had OpenSSL project, and it was fixed by this commit. It resolved my issue as well.

[sreimers]

It looks netdb.h related, can you try:

diff --git a/src/tcp/tcp.c b/src/tcp/tcp.c
index 15de2eec..23dc10d7 100644
--- a/src/tcp/tcp.c
+++ b/src/tcp/tcp.c
@@ -14,6 +14,7 @@
 #define __USE_POSIX 1  /**< Use POSIX flag */
 #define __USE_XOPEN2K 1/**< Use POSIX.1:2001 code */
 #define __USE_MISC 1
+#define _GNU_SOURCE 1
 #include <netdb.h>
 #endif
 #ifdef __APPLE__

[widgetii]

This work as well, changed