Fix a couple of warnings of errors in MSVC builds

Two warnings (in tests & examples) in particular would cause problems:
bad format causing invalid data output or a bad chdir due to out of
scope buffer use.

example/scp_nonblock.c

@@ -231,7 +231,6 @@ int main(int argc, char *argv[])
 
     while(got < fileinfo.st_size) {
         char mem[1024*24];
-        int rc;
 
         do {
             int amount = sizeof(mem);

example/scp_write.c

@@ -48,10 +48,10 @@ int main(int argc, char *argv[])
     size_t nread;
     char *ptr;
     struct stat fileinfo;
+    int err;
 
 #ifdef WIN32
     WSADATA wsadata;
-    int err;
 
     err = WSAStartup(MAKEWORD(2, 0), &wsadata);
     if(err != 0) {
@@ -165,7 +165,7 @@ int main(int argc, char *argv[])
     if(!channel) {
         char *errmsg;
         int errlen;
-        int err = libssh2_session_last_error(session, &errmsg, &errlen, 0);
+        err = libssh2_session_last_error(session, &errmsg, &errlen, 0);
         fprintf(stderr, "Unable to open a session: (%d) %s\n", err, errmsg);
         goto shutdown;
     }

example/sftpdir.c

@@ -37,7 +37,7 @@
 #include <ctype.h>
 
 #ifdef WIN32
-#define __FILESIZE "I64"
+#define __FILESIZE "I64u"
 #else
 #define __FILESIZE "llu"
 #endif

example/sftpdir_nonblock.c

@@ -37,7 +37,7 @@
 #include <ctype.h>
 
 #ifdef WIN32
-#define __FILESIZE "I64"
+#define __FILESIZE "I64u"
 #else
 #define __FILESIZE "llu"
 #endif

example/ssh2_agent_forwarding.c

@@ -225,7 +225,6 @@ int main(int argc, char *argv[])
     }
     for(;;) {
         /* loop until we block */
-        int rc;
         do {
             char buffer[0x4000];
             rc = libssh2_channel_read(channel, buffer, sizeof(buffer) );

example/ssh2_echo.c

@@ -250,8 +250,8 @@ int main(int argc, char *argv[])
         fds[0].events = LIBSSH2_POLLFD_POLLIN | LIBSSH2_POLLFD_POLLOUT;
 
         do {
-            int rc = (libssh2_poll(fds, 1, 10));
             int act = 0;
+            rc = (libssh2_poll(fds, 1, 10));
 
             if(rc < 1)
                 continue;

example/ssh2_exec.c

@@ -254,7 +254,6 @@ int main(int argc, char *argv[])
     }
     for(;;) {
         /* loop until we block */
-        int rc;
         do {
             char buffer[0x4000];
             rc = libssh2_channel_read(channel, buffer, sizeof(buffer) );

src/bcrypt_pbkdf.c

@@ -65,7 +65,7 @@ bcrypt_hash(uint8_t *sha2pass, uint8_t *sha2salt, uint8_t *out)
     uint32_t cdata[BCRYPT_BLOCKS];
     int i;
     uint16_t j;
-    size_t shalen = SHA512_DIGEST_LENGTH;
+    uint16_t shalen = SHA512_DIGEST_LENGTH;
 
     /* key expansion */
     Blowfish_initstate(&state);

src/packet.c

@@ -1392,7 +1392,7 @@ _libssh2_packet_requirev(LIBSSH2_SESSION *session,
 
         if(strchr((char *) packet_types, ret)) {
             /* Be lazy, let packet_ask pull it out of the brigade */
-            int ret = _libssh2_packet_askv(session, packet_types, data,
+            ret = _libssh2_packet_askv(session, packet_types, data,
                                        data_len, match_ofs, match_buf,
                                        match_len);
             state->start = 0;

tests/session_fixture.c

@@ -81,6 +81,11 @@ static int connect_to_server(void)
 
 static void setup_fixture_workdir(void)
 {
+#ifdef WIN32
+    char wd_buf[_MAX_PATH];
+#else
+    char wd_buf[MAXPATHLEN];
+#endif
     char *wd = getenv("FIXTURE_WORKDIR");
 #ifdef FIXTURE_WORKDIR
     if(!wd) {
@@ -88,11 +93,6 @@ static void setup_fixture_workdir(void)
     }
 #endif
     if(!wd) {
-#ifdef WIN32
-        char wd_buf[_MAX_PATH];
-#else
-        char wd_buf[MAXPATHLEN];
-#endif
         getcwd(wd_buf, sizeof(wd_buf));
         wd = wd_buf;
     }