all: add LLVM 22 support

Builder:
- Update clang.cpp for LLVM 22 API changes: DiagnosticOptions is no
  longer ref-counted, TextDiagnosticPrinter and DiagnosticsEngine take
  references instead of pointers, createDiagnostics() signature changed.
- Update cc1as.cpp: clang/Driver/Options.h moved to
  clang/Options/Options.h, namespace changed from clang::driver::options
  to clang::options, MCInstPrinter now passed as unique_ptr.
- Add new LLVM 22 libraries to GNUmakefile: clangAnalysisLifetimeSafety,
  clangOptions, LLVMDTLTO, and dtlto component.
- Add llvm22 build tag to all build/test commands.

CGo:
- Handle CXType_Unexposed in libclang.go by resolving via canonical
  type. LLVM 22 reports builtin type aliases (e.g. __size_t) as
  Unexposed instead of Typedef.
- Always make C typedefs into Go type aliases. LLVM 22 changed
  getTypedefDeclUnderlyingType to return CXType_Enum directly instead
  of wrapping in an elaborated type.

Compileopts:
- Add build-tag-guarded ClangTriple() to substitute wasm32-unknown-wasi
  with wasm32-unknown-wasip1 for LLVM 22 (deprecated triple).
- Add build-tag-guarded patchFeatures() to map renamed Xtensa features
  (atomctl, memctl, timerint, esp32s3) for LLVM 22.

Targets:
- Remove -zca from RISC-V target feature strings (esp32c3, esp32c6,
  fe310, k210, riscv-qemu, tkey). LLVM 22 now implies +zca from +c.
- Remove -zcd from k210. LLVM 22 now implies +zcd from +c,+d.

Tests:
- Change TestClangAttributes to check individual feature flags instead
  of exact string match, allowing new LLVM features without failures.
- Update TestBinarySize expected values for LLVM 22 codegen.

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

compileopts/features_llvm22.go

@@ -0,0 +1,26 @@
+//go:build llvm22
+
+package compileopts
+
+import "strings"
+
+// patchFeatures applies LLVM-version-specific feature name mappings.
+// LLVM 22 renamed several Xtensa target features.
+func patchFeatures(features string) string {
+	// Xtensa feature renames in LLVM 22:
+	//   atomctl → (removed, no direct replacement)
+	//   memctl  → (removed, no direct replacement)
+	//   esp32s3 → esp32s3ops
+	//   timerint → timers3 (for esp32/esp32s3) or timers1 (for esp8266)
+	// Since we can't distinguish which timer variant at this level,
+	// just remove the obsolete features. The CPU definition already
+	// implies the correct features in LLVM 22.
+	replacer := strings.NewReplacer(
+		"+atomctl,", "",
+		"+memctl,", "",
+		"+esp32s3,", "+esp32s3ops,",
+		"+timerint,", "",
+		",+timerint", "",
+	)
+	return replacer.Replace(features)
+}