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>

interp/memory.go

@@ -931,10 +931,10 @@ func (v rawValue) toLLVMValue(llvmType llvm.Type, mem *memoryView) (llvm.Value,
 				return llvm.Value{}, err
 			}
 		}
-		if llvmType.StructName() != "" {
-			return llvm.ConstNamedStruct(llvmType, fields), nil
-		}
-		return llvmType.Context().ConstStruct(fields, false), nil
+		// Always use ConstNamedStruct to preserve the exact type identity.
+		// ConstStruct creates a literal struct type which may differ from an
+		// anonymous identified struct even when structurally identical.
+		return llvm.ConstNamedStruct(llvmType, fields), nil
 	case llvm.ArrayTypeKind:
 		numElements := llvmType.ArrayLength()
 		childType := llvmType.ElementType()