community/wasm-micro-runtime: build with non-default llvm

Building with llvm 21 results in the error below. Support for llvm 21
upstream is in progress but does not appear to be ready at this time.
Rebuild with llvm 20 for now.

```
/home/buildozer/aports/community/wasm-micro-runtime/src/wasm-micro-runtime-WAMR-2.3.0/core/iwasm/compilation/aot_llvm.c: In function 'aot_create_comp_context':
/home/buildozer/aports/community/wasm-micro-runtime/src/wasm-micro-runtime-WAMR-2.3.0/core/iwasm/compilation/aot_llvm.c:2580:31: error: implicit declaration of function 'LLVMOrcThreadSafeContextGetContext' [-Wimplicit-function-declaration]
 2580 |     if (!(comp_ctx->context = LLVMOrcThreadSafeContextGetContext(
      |                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/buildozer/aports/community/wasm-micro-runtime/src/wasm-micro-runtime-WAMR-2.3.0/core/iwasm/compilation/aot_llvm.c:2580:29: error: assignment to 'LLVMContextRef' {aka 'struct LLVMOpaqueContext *'} from 'int' makes pointer from integer without a cast [-Wint-conversion]
 2580 |     if (!(comp_ctx->context = LLVMOrcThreadSafeContextGetContext(
      |                             ^
```

Ref: bytecodealliance/wasm-micro-runtime#4654

Author: mio

community/wasm-micro-runtime/APKBUILD

@@ -2,17 +2,20 @@
 # Maintainer: Jakub Jirutka <[email protected]>
 pkgname=wasm-micro-runtime
 pkgver=2.3.0
-pkgrel=0
+pkgrel=1
 pkgdesc="WebAssembly Micro Runtime (WAMR)"
 url="https://github.com/bytecodealliance/wasm-micro-runtime"
 # loongarch64,ppc64le,s390x: not supported by upstream
 arch="all !loongarch64 !ppc64le !s390x"
 license="Apache-2.0"
+# LLVM 21 support in progress
+# https://github.com/bytecodealliance/wasm-micro-runtime/pull/4654
+_llvmver=20
 makedepends="
 	cmake
-	llvm-dev
-	llvm-static
-	llvm-gtest
+	llvm$_llvmver-dev
+	llvm$_llvmver-static
+	llvm$_llvmver-gtest
 	samurai
 	"
 checkdepends="bash"