POSIX requires <sys/select.h> for select function.

A patch being applied to TXR in the Void Linux distribution
informs me that the Musl library requires this. Traditional
Unix put the select materials in <sys/types.h> and <unistd.h>.

* configure: Add test for presence of <sys/select.h> and
whether that header actually declares select-related
declarations and macros. Define HAVE_SYS_SELECT_H
in config.h if so.

* socket.c: Conditionally include <sys/select.h>.

1 files changed, 3 insertions, 0 deletions

diff --git a/socket.c b/socket.c
index 177c0e75..ace6944a 100644
--- a/socket.c
+++ b/socket.c
@@ -40,6 +40,9 @@
 #include <netdb.h>
 #include "config.h"
 #include ALLOCA_H
+#if HAVE_SYS_SELECT_H
+#include <sys/select.h>
+#endif
 #include "lib.h"
 #include "stream.h"
 #include "signal.h"