[haxe 4.3.4] build errors

I'm trying to compile Haxe 4.3.4 on a Mac M2 running Sequoia 15.1.1 and OCaml 5.2.1.
I've encountered some issues along the way, but I've managed to resolve most of them (#11787 #10679 #11874).

Now, I'm facing the following errors:

```
dune build --workspace dune-workspace.dev src-prebuild/prebuild.exe
_build/default/src-prebuild/prebuild.exe libparams -cclib -lpcre2-8 -cclib -lz -cclib -lmbedtls -cclib -lmbedx509 -cclib -lmbedcrypto -cclib '-framework Security -framework CoreFoundation' > lib.sexp
_build/default/src-prebuild/prebuild.exe version "0" "b4.3.4" "dc1a43dc5" > src/compiler/version.ml
dune build --workspace dune-workspace.dev src/haxe.exe
File "libs/pcre2/dune", line 7, characters 9-20:
7 | (names pcre2_stubs))
^^^^^^^^^^^
pcre2_stubs.c:57:10: fatal error: 'pcre2.h' file not found
57 | #include
| ^~~~~~~~~
1 error generated.
File "libs/mbedtls/dune", line 7, characters 9-22:
7 | (names mbedtls_stubs))
^^^^^^^^^^^^^
mbedtls_stubs.c:21:10: fatal error: 'mbedtls/debug.h' file not found
21 | #include "mbedtls/debug.h"
| ^~~~~~~~~~~~~~~~~
```

I've installed both `pcre2` and `mbedtls@2` through Homebrew.
Here are the installation details:

```
==> pcre2: stable 10.44 (bottled), HEAD
Perl compatible regular expressions library with a new API
https://www.pcre.org/
Installed
/opt/homebrew/Cellar/pcre2/10.44 (237 files, 6.3MB) *
Poured from bottle using the formulae.brew.sh API on 2024-08-27 at 09:21:42
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/p/pcre2.rb
```

```
==> mbedtls@2: stable 2.28.9 (bottled), HEAD [keg-only]
Cryptographic & SSL/TLS library
https://tls.mbed.org/
Installed
/opt/homebrew/Cellar/mbedtls@2/2.28.9 (188 files, 8.3MB)
Poured from bottle using the formulae.brew.sh API on 2024-12-12 at 08:56:51
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/m/mbedtls@2.rb
```

I've also tried setting the LDFLAGS and CPPFLAGS variables to the library locations, but it seems the build script does not use them.

Start with libs/pcre2/dune and libs/mbedtls/dune, then reproduce the reported dune build commands on macOS. Check how these stubs locate the installed PCRE2 and mbedTLS headers; done means the Haxe build proceeds without the missing pcre2.h and mbedtls/debug.h errors.

Written by the indexing model from the issue text.