Explicitly closing logctx on various kinds of error exit means that

the log file gets fclosed properly and the critical last few
messages might be recoverable from the log file more often...

[originally from svn r6834]

unix/uxplink.c

@@ -25,6 +25,8 @@
 
 #define MAX_STDIN_BACKLOG 4096
 
+void *logctx;
+
 void fatalbox(char *p, ...)
 {
     va_list ap;
@@ -33,6 +35,10 @@ void fatalbox(char *p, ...)
     vfprintf(stderr, p, ap);
     va_end(ap);
     fputc('\n', stderr);
+    if (logctx) {
+        log_free(logctx);
+        logctx = NULL;
+    }
     cleanup_exit(1);
 }
 void modalfatalbox(char *p, ...)
@@ -43,6 +49,10 @@ void modalfatalbox(char *p, ...)
     vfprintf(stderr, p, ap);
     va_end(ap);
     fputc('\n', stderr);
+    if (logctx) {
+        log_free(logctx);
+        logctx = NULL;
+    }
     cleanup_exit(1);
 }
 void connection_fatal(void *frontend, char *p, ...)
@@ -53,6 +63,10 @@ void connection_fatal(void *frontend, char *p, ...)
     vfprintf(stderr, p, ap);
     va_end(ap);
     fputc('\n', stderr);
+    if (logctx) {
+        log_free(logctx);
+        logctx = NULL;
+    }
     cleanup_exit(1);
 }
 void cmdline_error(char *p, ...)
@@ -556,7 +570,7 @@ int main(int argc, char **argv)
     int exitcode;
     int errors;
     int use_subsystem = 0;
-    void *ldisc, *logctx;
+    void *ldisc;
     long now;
 
     fdlist = NULL;

windows/winplink.c

@@ -29,6 +29,10 @@ void fatalbox(char *p, ...)
     vfprintf(stderr, p, ap);
     va_end(ap);
     fputc('\n', stderr);
+    if (logctx) {
+        log_free(logctx);
+        logctx = NULL;
+    }
     cleanup_exit(1);
 }
 void modalfatalbox(char *p, ...)
@@ -39,6 +43,10 @@ void modalfatalbox(char *p, ...)
     vfprintf(stderr, p, ap);
     va_end(ap);
     fputc('\n', stderr);
+    if (logctx) {
+        log_free(logctx);
+        logctx = NULL;
+    }
     cleanup_exit(1);
 }
 void connection_fatal(void *frontend, char *p, ...)
@@ -49,6 +57,10 @@ void connection_fatal(void *frontend, char *p, ...)
     vfprintf(stderr, p, ap);
     va_end(ap);
     fputc('\n', stderr);
+    if (logctx) {
+        log_free(logctx);
+        logctx = NULL;
+    }
     cleanup_exit(1);
 }
 void cmdline_error(char *p, ...)