internal/rosa/llvm: exclude benchmarks

These are being built despite LLVM_BUILD_BENCHMARKS defaulting to off.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/llvm.go

@@ -174,6 +174,7 @@ func (t Toolchain) newLLVM() (pkg.Artifact, string) {
 		{"LLVM_ENABLE_ZLIB", "FORCE_ON"},
 		{"LLVM_ENABLE_ZSTD", "FORCE_ON"},
 		{"LLVM_ENABLE_PER_TARGET_RUNTIME_DIR", "ON"},
+		{"LLVM_INCLUDE_BENCHMARKS", "OFF"},
 		{"CLANG_DEFAULT_RTLIB", "compiler-rt"},
 		{"CLANG_DEFAULT_UNWINDLIB", "libunwind"},
 		{"CLANG_DEFAULT_CXX_STDLIB", "libc++"},