Fix JSCOnly build of bmalloc

[bnham]

75b8547

Fix JSCOnly build of bmalloc
https://bugs.webkit.org/show_bug.cgi?id=244751
<rdar://problem/99556286>

Reviewed by Yusuke Suzuki.

In bug 244355 we made `bmalloc::api::enableMiniMode()` call a function in ProcessCheck. But this
breaks the JSCOnly CMake port because ProcessCheck wasn't compiled for that port (it was only
compiled for the Mac port). This patch fixes that.

* Source/bmalloc/PlatformJSCOnly.cmake: Added.

Canonical link: https://commits.webkit.org/254194@main

69c1241

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	🛠 mac	✅ 🛠 wpe	🛠 🧪 win
	✅ 🛠 ios-sim	🛠 mac-debug	✅ 🛠 gtk	🛠 wincairo
✅ 🧪 webkitperl	🧪 ios-wk2	🛠 mac-AS-debug	🧪 gtk-wk2
	🧪 api-ios	🧪 api-mac	🧪 api-gtk
✅ 🛠 🧪 jsc	🛠 tv	🧪 mac-wk1	✅ 🛠 jsc-armv7
	🛠 tv-sim	🧪 mac-wk2	✅ 🧪 jsc-armv7-tests
✅ 🛠 🧪 merge	✅ 🛠 watch	🧪 mac-AS-debug-wk2	✅ 🛠 jsc-mips
	✅ 🛠 watch-sim	🧪 mac-wk2-stress	✅ 🧪 jsc-mips-tests

[webkit-early-warning-system]

EWS run on previous version of this PR (hash db26375)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 🧪 win
	✅ 🛠 ios-sim	✅ 🛠 mac-debug	✅ 🛠 gtk	✅ 🛠 wincairo
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🛠 mac-AS-debug	✅ 🧪 gtk-wk2
	✅ 🧪 api-ios	✅ 🧪 api-mac	✅ 🧪 api-gtk
✅ 🛠 🧪 jsc	✅ 🛠 tv	✅ 🧪 mac-wk1	✅ 🛠 jsc-armv7
	✅ 🛠 tv-sim	✅ 🧪 mac-wk2	✅ 🧪 jsc-armv7-tests
❌ 🛠 🧪 merge	✅ 🛠 watch	✅ 🧪 mac-AS-debug-wk2	✅ 🛠 jsc-mips
	✅ 🛠 watch-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 jsc-mips-tests

[Constellation]

r=me

[webkit-commit-queue]

No reviewer information in commit message, blocking PR #4015

[webkit-early-warning-system]

69c1241

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	🛠 mac	✅ 🛠 wpe	🛠 🧪 win
	✅ 🛠 ios-sim	🛠 mac-debug	✅ 🛠 gtk	🛠 wincairo
✅ 🧪 webkitperl	🧪 ios-wk2	🛠 mac-AS-debug	🧪 gtk-wk2
	🧪 api-ios	🧪 api-mac	🧪 api-gtk
✅ 🛠 🧪 jsc	🛠 tv	🧪 mac-wk1	✅ 🛠 jsc-armv7
	🛠 tv-sim	🧪 mac-wk2	✅ 🧪 jsc-armv7-tests
✅ 🛠 🧪 merge	✅ 🛠 watch	🧪 mac-AS-debug-wk2	✅ 🛠 jsc-mips
	✅ 🛠 watch-sim	🧪 mac-wk2-stress	✅ 🧪 jsc-mips-tests

[webkit-commit-queue]

Committed 254194@main (75b8547): https://commits.webkit.org/254194@main

Reviewed commits have been landed. Closing PR #4015 and removing active labels.