src: fix potential macro confusion in cmake unity builds

Sources used `lib/curlx.h` with both `ENABLE_CURLX_PRINTF` set and unset
before including it.

In a cmake "unity" batch where the first included source had it unset,
the next sources did not get the macros requested with
`ENABLE_CURLX_PRINTF` because `lib/curl.x` had already been included
without them.

Fix it by by making the macros enabled permanently and globally for
internal sources, and dropping `ENABLE_CURLX_PRINTF`.

This came up while testing unity builds with smaller batches. The full,
default unity build where all `src` is bundled up in a single unit, was
not affected.

Fixes:
```
$ cmake -B build -DCMAKE_UNITY_BUILD=ON -DCMAKE_UNITY_BUILD_BATCH_SIZE=15
$ make -C build
...
curl/src/tool_getparam.c: In function ‘getparameter’:
curl/src/tool_getparam.c:2409:11: error: implicit declaration of function ‘msnprintf’; did you mean ‘vsnprintf’? [-Wimplicit-function-declaration]
 2409 |           msnprintf(buffer, sizeof(buffer), "%" CURL_FORMAT_CURL_OFF_T "-",
      |           ^~~~~~~~~
      |           vsnprintf
curl/src/tool_getparam.c:2409:11: warning: nested extern declaration of ‘msnprintf’ [-Wnested-externs]
[...]
```

Reported-by: Daniel Stenberg
Bug: https://github.com/curl/curl/pull/14626#issuecomment-2301663491

Closes #14632

tests/server/fake_ntlm.c

@@ -31,7 +31,6 @@
  * responses with a pre-written string saved in test case test2005.
  */
 
-#define ENABLE_CURLX_PRINTF
 #include "curlx.h" /* from the private lib dir */
 #include "getpart.h"
 #include "util.h"

tests/server/getpart.c

@@ -25,9 +25,6 @@
 
 #include "getpart.h"
 
-#define ENABLE_CURLX_PRINTF
-/* make the curlx header define all printf() functions to use the curlx_*
-   versions instead */
 #include "curlx.h" /* from the private lib dir */
 
 /* just to please curl_base64.h we create a fake struct */

tests/server/mqttd.c

@@ -54,9 +54,6 @@
 #include <netdb.h>
 #endif
 
-#define ENABLE_CURLX_PRINTF
-/* make the curlx header define all printf() functions to use the curlx_*
-   versions instead */
 #include "curlx.h" /* from the private lib dir */
 #include "getpart.h"
 #include "inet_pton.h"

tests/server/resolve.c

@@ -45,9 +45,6 @@
 #include <netdb.h>
 #endif
 
-#define ENABLE_CURLX_PRINTF
-/* make the curlx header define all printf() functions to use the curlx_*
-   versions instead */
 #include "curlx.h" /* from the private lib dir */
 #include "util.h"
 

tests/server/rtspd.c

@@ -46,9 +46,6 @@
 #include <netinet/tcp.h> /* for TCP_NODELAY */
 #endif
 
-#define ENABLE_CURLX_PRINTF
-/* make the curlx header define all printf() functions to use the curlx_*
-   versions instead */
 #include "curlx.h" /* from the private lib dir */
 #include "getpart.h"
 #include "util.h"

tests/server/sockfilt.c

@@ -99,9 +99,6 @@
 #include <netdb.h>
 #endif
 
-#define ENABLE_CURLX_PRINTF
-/* make the curlx header define all printf() functions to use the curlx_*
-   versions instead */
 #include "curlx.h" /* from the private lib dir */
 #include "getpart.h"
 #include "inet_pton.h"

tests/server/socksd.c

@@ -71,9 +71,6 @@
 #include <netdb.h>
 #endif
 
-#define ENABLE_CURLX_PRINTF
-/* make the curlx header define all printf() functions to use the curlx_*
-   versions instead */
 #include "curlx.h" /* from the private lib dir */
 #include "getpart.h"
 #include "inet_pton.h"

tests/server/sws.c

@@ -47,9 +47,6 @@
 #include <netinet/tcp.h> /* for TCP_NODELAY */
 #endif
 
-#define ENABLE_CURLX_PRINTF
-/* make the curlx header define all printf() functions to use the curlx_*
-   versions instead */
 #include "curlx.h" /* from the private lib dir */
 #include "getpart.h"
 #include "inet_pton.h"

tests/server/tftpd.c

@@ -81,9 +81,6 @@
 
 #include <ctype.h>
 
-#define ENABLE_CURLX_PRINTF
-/* make the curlx header define all printf() functions to use the curlx_*
-   versions instead */
 #include "curlx.h" /* from the private lib dir */
 #include "getpart.h"
 #include "util.h"

tests/server/util.c

@@ -40,9 +40,6 @@
 #include <sys/poll.h>
 #endif
 
-#define ENABLE_CURLX_PRINTF
-/* make the curlx header define all printf() functions to use the curlx_*
-   versions instead */
 #include "curlx.h" /* from the private lib dir */
 #include "getpart.h"
 #include "util.h"