tests/server: make string literals const

assign string literals to const char * instead of char * in order to
avoid a lot of these warnings:
cast from 'const char *' to 'char *' drops const qualifier
[-Wcast-qual]

tests/server/fake_ntlm.c

@@ -120,9 +120,9 @@ int main(int argc, char *argv[])
   long testnum;
   const char *env;
   int arg = 1;
-  char *helper_user = (char *)"unknown";
+  const char *helper_user = "unknown";
-  char *helper_proto = (char *)"unknown";
+  const char *helper_proto = "unknown";
-  char *helper_domain = (char *)"unknown";
+  const char *helper_domain = "unknown";
   bool use_cached_creds = FALSE;
   char *msgbuf;
 

tests/server/rtspd.c

@@ -1190,7 +1190,7 @@ int main(int argc, char *argv[])
   int wrotepidfile = 0;
   int flag;
   unsigned short port = DEFAULT_PORT;
-  char *pidname= (char *)".rtsp.pid";
+  const char *pidname = ".rtsp.pid";
   struct httprequest req;
   int rc;
   int error;

tests/server/sockfilt.c

@@ -405,7 +405,7 @@ static ssize_t fullwrite(int filedes, const void *buffer, size_t nbytes)
   ssize_t nwrite = 0;
 
   do {
-    wc = write(filedes, (unsigned char *)buffer + nwrite, nbytes - nwrite);
+    wc = write(filedes, (const unsigned char *)buffer + nwrite, nbytes - nwrite);
 
     if(got_exit_signal) {
       logmsg("signalled to die");
@@ -1338,7 +1338,7 @@ int main(int argc, char *argv[])
   curl_socket_t sock = CURL_SOCKET_BAD;
   curl_socket_t msgsock = CURL_SOCKET_BAD;
   int wrotepidfile = 0;
-  char *pidname= (char *)".sockfilt.pid";
+  const char *pidname = ".sockfilt.pid";
   bool juggle_again;
   int rc;
   int error;

tests/server/sws.c

@@ -130,7 +130,7 @@ static curl_socket_t all_sockets[MAX_SOCKETS];
 static size_t num_sockets = 0;
 
 static int ProcessRequest(struct httprequest *req);
-static void storerequest(char *reqbuf, size_t totalsize);
+static void storerequest(const char *reqbuf, size_t totalsize);
 
 #define DEFAULT_PORT 8999
 
@@ -843,7 +843,7 @@ static int ProcessRequest(struct httprequest *req)
 }
 
 /* store the entire request in a file */
-static void storerequest(char *reqbuf, size_t totalsize)
+static void storerequest(const char *reqbuf, size_t totalsize)
 {
   int res;
   int error = 0;
@@ -1965,7 +1965,7 @@ int main(int argc, char *argv[])
   const char *unix_socket = NULL;
   bool unlink_socket = false;
 #endif
-  char *pidname= (char *)".http.pid";
+  const char *pidname = ".http.pid";
   struct httprequest req;
   int rc = 0;
   int error;
@@ -2315,7 +2315,7 @@ int main(int argc, char *argv[])
 
             if(req.connmon) {
               const char *keepopen="[DISCONNECT]\n";
-              storerequest((char *)keepopen, strlen(keepopen));
+              storerequest(keepopen, strlen(keepopen));
             }
 
             if(!req.open)

tests/server/tftpd.c

@@ -208,7 +208,7 @@ static bool use_ipv6 = FALSE;
 static const char *ipv_inuse = "IPv4";
 
 const  char *serverlogfile = DEFAULT_LOGFILE;
-static char *pidname= (char *)".tftpd.pid";
+static const char *pidname = ".tftpd.pid";
 static int serverlogslocked = 0;
 static int wrotepidfile = 0;
 
@@ -960,7 +960,7 @@ static int do_tftp(struct testcase *test, struct tftphdr *tp, ssize_t size)
 #ifdef USE_WINSOCK
   DWORD recvtimeout, recvtimeoutbak;
 #endif
-  char *option = (char *)"mode"; /* mode is implicit */
+  const char *option = "mode"; /* mode is implicit */
   int toggle = 1;
 
   /* Open request dump file. */