Seen with llvm 17 on Windows.

```
.../curl/tests/server/rtspd.c:136:13: warning: no previous extern declaration for non-static variable 'logdir' [-Wmissing-variable-declarations]
  136 | const char *logdir = "log";
      |             ^
.../curl/tests/server/rtspd.c:136:7: note: declare 'static' if the variable is not intended to be used outside of this translation unit
  136 | const char *logdir = "log";
      |       ^
.../curl/tests/server/rtspd.c:137:6: warning: no previous extern declaration for non-static variable 'loglockfile' [-Wmissing-variable-declarations]
  137 | char loglockfile[256];
      |      ^
.../curl/tests/server/rtspd.c:137:1: note: declare 'static' if the variable is not intended to be used outside of this translation unit
  137 | char loglockfile[256];
      | ^
.../curl/tests/server/fake_ntlm.c:43:13: warning: no previous extern declaration for non-static variable 'logdir' [-Wmissing-variable-declarations]
   43 | const char *logdir = "log";
      |             ^
.../curl/tests/server/fake_ntlm.c:43:7: note: declare 'static' if the variable is not intended to be used outside of this translation unit
   43 | const char *logdir = "log";
      |       ^
.../curl/src/tool_doswin.c:350:8: warning: possible misuse of comma operator here [-Wcomma]
  350 |     ++d, ++s;
      |        ^
.../curl/src/tool_doswin.c:350:5: note: cast expression to void to silence warning
  350 |     ++d, ++s;
      |     ^~~
      |     (void)( )
```

Closes #xxxxx

```
.../curl/tests/server/sws.c:440:64: warning: field precision should have type 'int', but argument has type 'size_t' (aka 'unsigned long') [-Wformat]
          msnprintf(logbuf, sizeof(logbuf), "Got request: %s %.*s HTTP/%d.%d",
                                                             ~~^~
1 warning generated.
```

Seen with llvm 17 for Windows x64.

```
.../curl/tests/libtest/lib540.c:146:27: warning: result of comparison 'long' > 2147483647 is always false [-Wtautological-type-limit-compare]
  146 |         int itimeout = (L > (long)INT_MAX) ? INT_MAX : (int)L;
      |                         ~ ^ ~~~~~~~~~~~~~
1 warning generated.

.../curl/tests/libtest/libntlmconnect.c:195:31: warning: result of comparison 'long' > 2147483647 is always false [-Wtautological-type-limit-compare]
  195 |       int itimeout = (timeout > (long)INT_MAX) ? INT_MAX : (int)timeout;
      |                       ~~~~~~~ ^ ~~~~~~~~~~~~~
1 warning generated.

.../curl/tests/libtest/lib591.c:117:31: warning: result of comparison 'long' > 2147483647 is always false [-Wtautological-type-limit-compare]
  117 |       int itimeout = (timeout > (long)INT_MAX) ? INT_MAX : (int)timeout;
      |                       ~~~~~~~ ^ ~~~~~~~~~~~~~
1 warning generated.
.../curl/tests/libtest/lib597.c:99:31: warning: result of comparison 'long' > 2147483647 is always false [-Wtautological-type-limit-compare]
   99 |       int itimeout = (timeout > (long)INT_MAX) ? INT_MAX : (int)timeout;
      |                       ~~~~~~~ ^ ~~~~~~~~~~~~~
1 warning generated.
```

Fix based on 3186f50.