all: fix LLVM version compatibility for targets and interp

cc1as: change AssemblerInvocation.Triple from std::string to
llvm::Triple, matching upstream LLVM 22 and fixing deprecation warnings
for lookupTarget, createMCRegInfo, createMCAsmInfo, and
createMCSubtargetInfo.

interp: always use ConstNamedStruct in rawValue.toLLVMValue instead of
falling back to ConstStruct for unnamed structs. LLVM 22 uses anonymous
identified struct types where previous versions used literal structs;
ConstStruct creates a literal type that doesn't match, causing an
"initializer type mismatch" panic for globals like fmt.ppFree.

compileopts: add build-tag-guarded feature patching for pre-LLVM 20
(strip +bulk-memory-opt and +call-indirect-overlong from wasm features)
and restructure into three files covering all LLVM version ranges.

targets: strip redundant negative features from RISC-V target JSONs
(esp32c3, esp32c6, fe310, k210, riscv-qemu, tkey). These ~190 negative
features per target listed every extension LLVM knows about that the
target doesn't use, but LLVM disables them by default. They became stale
across LLVM versions, causing "not a recognized feature" warnings. Keep
only positive features and -relax.

Signed-off-by: deadprogram <ron@hybridgroup.com>

compileopts/features_default.go

@@ -0,0 +1,9 @@
+//go:build !llvm22 && !llvm14 && !llvm15 && !llvm16 && !llvm17 && !llvm18 && !llvm19
+
+package compileopts
+
+// patchFeatures applies LLVM-version-specific feature name mappings.
+// For LLVM 20/21, features in the target JSON files are already correct.
+func patchFeatures(features string) string {
+	return features
+}

compileopts/features_pre20.go

@@ -0,0 +1,16 @@
+//go:build llvm14 || llvm15 || llvm16 || llvm17 || llvm18 || llvm19
+
+package compileopts
+
+import "strings"
+
+// patchFeatures applies LLVM-version-specific feature name mappings.
+// LLVM 19 and earlier do not have +bulk-memory-opt or
+// +call-indirect-overlong for WebAssembly (added in LLVM 20).
+func patchFeatures(features string) string {
+	features = strings.ReplaceAll(features, ",+bulk-memory-opt", "")
+	features = strings.ReplaceAll(features, "+bulk-memory-opt,", "")
+	features = strings.ReplaceAll(features, ",+call-indirect-overlong", "")
+	features = strings.ReplaceAll(features, "+call-indirect-overlong,", "")
+	return features
+}

compileopts/features_pre22.go

@@ -1,9 +0,0 @@
-//go:build !llvm22
-
-package compileopts
-
-// patchFeatures applies LLVM-version-specific feature name mappings.
-// For pre-LLVM 22, no patching is needed.
-func patchFeatures(features string) string {
-	return features
-}