Unreviewed build fixes for RISCV64

[zdobersek]

c07cdb6

Unreviewed build fixes for RISCV64
https://bugs.webkit.org/show_bug.cgi?id=253700

Unreviewed build fixes for RISCV64 builds of JavaScriptCore.

* Source/JavaScriptCore/assembler/MacroAssembler.h: Enable the moveFloat and
moveDouble methods that work with immediate values, sharing the scratch register
variant with x86-64.
* Source/JavaScriptCore/offlineasm/riscv64.rb: Also generate WASM placeholders
for the loadv and storev opcodes, used in WebAssembly.asm.
* Source/WTF/wtf/PlatformEnable.h: Avoid further compilation issues by enabling
ENABLE_WEBASSEMBLY_B3JIT alongside ENABLE_WEBASSEMBLY.

Canonical link: https://commits.webkit.org/261498@main

7c6cc12

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2
✅ 🧪 webkitperl	🧪 ios-wk2	✅ 🧪 api-mac	✅ 🛠 gtk
	✅ 🧪 api-ios	🧪 mac-wk1	🧪 gtk-wk2
✅ 🛠 🧪 jsc	✅ 🛠 tv	✅ 🧪 mac-wk2	🧪 api-gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv-sim	🧪 mac-AS-debug-wk2	✅ 🛠 jsc-armv7
	✅ 🛠 watch	✅ 🧪 mac-wk2-stress	✅ 🧪 jsc-armv7-tests
✅ 🛠 🧪 merge	✅ 🛠 watch-sim		✅ 🛠 jsc-mips
			✅ 🧪 jsc-mips-tests

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 5349b56)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2
✅ 🧪 webkitperl	🧪 ios-wk2	🧪 api-mac	✅ 🛠 gtk
	🧪 api-ios	🧪 mac-wk1	🧪 gtk-wk2
✅ 🛠 🧪 jsc	✅ 🛠 tv	🧪 mac-wk2	🧪 api-gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv-sim	🧪 mac-AS-debug-wk2	✅ 🛠 jsc-armv7
	✅ 🛠 watch	🧪 mac-wk2-stress	✅ 🧪 jsc-armv7-tests
	✅ 🛠 watch-sim		✅ 🛠 jsc-mips
			🧪 jsc-mips-tests

[webkit-early-warning-system]

EWS run on current version of this PR (hash 7c6cc12)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2
✅ 🧪 webkitperl	🧪 ios-wk2	✅ 🧪 api-mac	✅ 🛠 gtk
	✅ 🧪 api-ios	🧪 mac-wk1	🧪 gtk-wk2
✅ 🛠 🧪 jsc	✅ 🛠 tv	✅ 🧪 mac-wk2	🧪 api-gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv-sim	🧪 mac-AS-debug-wk2	✅ 🛠 jsc-armv7
	✅ 🛠 watch	✅ 🧪 mac-wk2-stress	✅ 🧪 jsc-armv7-tests
✅ 🛠 🧪 merge	✅ 🛠 watch-sim		✅ 🛠 jsc-mips
			✅ 🧪 jsc-mips-tests

[webkit-commit-queue]

Committed 261498@main (c07cdb6): https://commits.webkit.org/261498@main

Reviewed commits have been landed. Closing PR #11358 and removing active labels.