lib: make CURLX_SET_BINMODE() and use it

Use it from libtests' `first.c` and thus also from units, and tunits.

Also:
- cmake: drop stray `curltool` lib dependency for units.
- units: stop depending on `src` headers.
- tests/server: drop depending on `src` headers.
  (the remaining one listed in the comments, `tool_xattr.h`, was not
  actually used from servers.)
- tests/server: drop duplicate curlx headers.
  (Except `warnless.h`, which is tricky on Windows.)

Closes #17672

src/tool_getparam.c

@@ -24,7 +24,6 @@
 #include "tool_setup.h"
 
 #include <curlx.h>
-#include "tool_binmode.h"
 #include "tool_cfgable.h"
 #include "tool_cb_prg.h"
 #include "tool_filetime.h"
@@ -625,7 +624,7 @@ static ParameterError data_urlencode(struct GlobalConfig *global,
     /* a '@' letter, it means that a filename or - (stdin) follows */
     if(!strcmp("-", p)) {
       file = stdin;
-      CURL_SET_BINMODE(stdin);
+      CURLX_SET_BINMODE(stdin);
     }
     else {
       file = fopen(p, "rb");
@@ -901,7 +900,7 @@ static ParameterError set_data(cmdline_t cmd,
     if(!strcmp("-", nextarg)) {
       file = stdin;
       if(cmd == C_DATA_BINARY) /* forced data-binary */
-        CURL_SET_BINMODE(stdin);
+        CURLX_SET_BINMODE(stdin);
     }
     else {
       file = fopen(nextarg, "rb");