PCRE2 JIT compilation is unsupported on iOS as per
https://codereview.qt-project.org/c/qt/qtbase/+/204514
Since our Qt port uses the separately built `pcre2` port (instead of the
bundled version):
3f966cf6a8/ports/qtbase/portfile.cmake (L315)
...the linked Qt fix doesn't apply to us, so we'll have to disable it
explicitly.
### Background
I ran into this today while debugging a crash of a Qt app built for the
iOS simulator (using vcpkg-built libraries):
<details>
<summary>Crash Log</summary>
```
Exception Type: EXC_BAD_ACCESS (SIGBUS)
Exception Subtype: KERN_PROTECTION_FAILURE at 0x000000010dbb8008
Exception Codes: 0x0000000000000002, 0x000000010dbb8008
VM Region Info: 0x10dbb8008 is in 0x10dbb8000-0x10dbc8000; bytes after start: 8 bytes before end: 65527
REGION TYPE START - END [ VSIZE] PRT/MAX SHRMOD REGION DETAIL
ColorSync 10dbb0000-10dbb8000 [ 32K] r--/r-- SM=PRV
---> VM_ALLOCATE 10dbb8000-10dbc8000 [ 64K] rwx/rwx SM=PRV
GAP OF 0x38000 BYTES
MALLOC_TINY 10dc00000-10dd00000 [ 1024K] rw-/rwx SM=PRV
Termination Reason: SIGNAL 10 Bus error: 10
Terminating Process: exc handler [98229]
Triggered by Thread: 0
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 Mixxx 0x107b8ec24 sljit_malloc_exec + 236
1 Mixxx 0x107b8ea80 pcre2_jit_compile_16 + 160
2 Mixxx 0x104ec52d4 QRegularExpressionPrivate::compilePattern() + 252
3 Mixxx 0x104ec6058 QRegularExpression::isValid() const + 24
4 Mixxx 0x104e30194 QtPrivate::contains(QStringView, QString const*, QRegularExpression const&, QRegularExpressionMatch*) + 52
5 Mixxx 0x10599a8ec QIOSScreen::QIOSScreen(UIScreen*) + 1060
6 Mixxx 0x105998850 QIOSIntegration::initialize() + 272
7 Mixxx 0x104d8165c QCoreApplicationPrivate::init() + 1640
8 Mixxx 0x1076c80e0 QGuiApplicationPrivate::init() + 60
9 Mixxx 0x105d9d20c QApplicationPrivate::init() + 24
10 Mixxx 0x105d9d1e0 QApplication::QApplication(int&, char**, int) + 140
```
</details>
This fixes the problem.
### Checklist
- [x] Changes comply with the [maintainer
guide](https://github.com/microsoft/vcpkg-docs/blob/main/vcpkg/contributing/maintainer-guide.md).
- [x] SHA512s are updated for each updated download (not applicable).
- [x] The "supports" clause reflects platforms that may be fixed by this
new version.
- [x] Any fixed [CI
baseline](https://github.com/microsoft/vcpkg/blob/master/scripts/ci.baseline.txt)
entries are removed from that file (not applicable).
- [x] Any patches that are no longer applied are deleted from the port's
directory (not applicable).
- [x] The version database is fixed by rerunning `./vcpkg x-add-version
--all` and committing the result.
- [x] Only one version is added to each modified port's versions file.