tidy-up: example, tests

- drop unnecessary `WIN32`-specific branches.

- add `static`.

- sync header inclusion order.

- sync some common code between examples/tests.

- fix formatting/indentation.

- fix some `checksrc` errors not caught by `checksrc`.

Closes #936

example/sftp_mkdir_nonblock.c

@@ -14,12 +14,12 @@
 #ifdef HAVE_SYS_SOCKET_H
 #include <sys/socket.h>
 #endif
-#ifdef HAVE_NETINET_IN_H
-#include <netinet/in.h>
-#endif
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
 #ifdef HAVE_ARPA_INET_H
 #include <arpa/inet.h>
 #endif
@@ -38,6 +38,8 @@ int main(int argc, char *argv[])
     struct sockaddr_in sin;
     const char *fingerprint;
     LIBSSH2_SESSION *session;
+    const char *pubkey = "/home/username/.ssh/id_rsa.pub";
+    const char *privkey = "/home/username/.ssh/id_rsa";
     const char *username = "username";
     const char *password = "password";
     const char *sftppath = "/tmp/sftp_mkdir_nonblock";
@@ -61,7 +63,6 @@ int main(int argc, char *argv[])
     else {
         hostaddr = htonl(0x7F000001);
     }
-
     if(argc > 2) {
         username = argv[2];
     }
@@ -87,8 +88,7 @@ int main(int argc, char *argv[])
     sin.sin_family = AF_INET;
     sin.sin_port = htons(22);
     sin.sin_addr.s_addr = hostaddr;
-    if(connect(sock, (struct sockaddr*)(&sin),
-            sizeof(struct sockaddr_in)) != 0) {
+    if(connect(sock, (struct sockaddr*)(&sin), sizeof(struct sockaddr_in))) {
         fprintf(stderr, "failed to connect!\n");
         return -1;
     }
@@ -130,9 +130,8 @@ int main(int argc, char *argv[])
     else {
         /* Or by public key */
         if(libssh2_userauth_publickey_fromfile(session, username,
-                            "/home/username/.ssh/id_rsa.pub",
-                            "/home/username/.ssh/id_rsa",
-                            password)) {
+                                               pubkey, privkey,
+                                               password)) {
             fprintf(stderr, "\tAuthentication by public key failed\n");
             goto shutdown;
         }
@@ -159,7 +158,7 @@ int main(int argc, char *argv[])
 
     libssh2_sftp_shutdown(sftp_session);
 
- shutdown:
+shutdown:
 
     libssh2_session_disconnect(session, "Normal Shutdown");
     libssh2_session_free(session);