curlx: limit use of system allocators to the minimum possible

Clone a multibye conversion function into curlx/fopen, and use that
local copy from curlx/fopen functions. Adjust allocators in curlx/fopen
to use curl's in normal builds, and system allocators in TrackMemory
builds to avoid recursion.

This allows to switch curlx/multibyte functions to curl allocators in
all configurations, as they are no longer called by curlx/fopen, and
a recursive call can no longer happen.

After this patch the system allocator is only used in TrackMemory
Windows builds, within curlx `fopen`, `freopen`, `stat` and `open`
functions.

Also:
- test 1, 440, 767: raise allocation limitsto fit the extra allocations
  in Windows Unicode builds.
- replace all uses of `curlx_unicodefree()` macro with `curlx_free()`
  across the codebase.
- curlx/multibyte: delete `curlx_unicodefree()`.
- ldap: join Windows and non-Windows codepaths that became
  identical after moving from `curlx_unicodefree()` to `curlx_free()`.
- vauth: drop a strdup from standard to curl allocator since
  the original allocation is now already done by curl's.
- tool_doswin: drop now superfluous strdup from `FindWin32CACert()`.
- memanalyzer.pm: sync weirdo `calloc` log message with `malloc`'s.

Fixes #19748
Closes #19845

lib/ldap.c

@@ -96,7 +96,7 @@
 #include "connect.h"
 
 #ifdef USE_WIN32_LDAP
-#define FREE_ON_WINLDAP(x) curlx_unicodefree(x)
+#define FREE_ON_WINLDAP(x) curlx_free(x)
 #define curl_ldap_num_t    ULONG
 #else
 #define FREE_ON_WINLDAP(x)
@@ -296,8 +296,8 @@ static ULONG ldap_win_bind(struct Curl_easy *data, LDAP *server,
 
     rc = ldap_simple_bind_s(server, inuser, inpass);
 
-    curlx_unicodefree(inuser);
-    curlx_unicodefree(inpass);
+    curlx_free(inuser);
+    curlx_free(inpass);
   }
 #ifdef USE_WINDOWS_SSPI
   else {
@@ -1000,22 +1000,13 @@ static void ldap_free_urldesc_low(LDAPURLDesc *ludp)
   if(!ludp)
     return;
 
-#ifdef USE_WIN32_LDAP
-  curlx_unicodefree(ludp->lud_dn);
-  curlx_unicodefree(ludp->lud_filter);
-#else
   curlx_free(ludp->lud_dn);
   curlx_free(ludp->lud_filter);
-#endif
 
   if(ludp->lud_attrs) {
     size_t i;
     for(i = 0; i < ludp->lud_attrs_dups; i++) {
-#ifdef USE_WIN32_LDAP
-      curlx_unicodefree(ludp->lud_attrs[i]);
-#else
       curlx_free(ludp->lud_attrs[i]);
-#endif
     }
     curlx_free(ludp->lud_attrs);
   }