internal/rosa/llvm: statically link libc++

This avoids unnecessarily depending on the toolchain.

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

internal/rosa/llvm.go

@@ -83,9 +83,11 @@ func init() {
 			{"LIBCXX_ENABLE_STATIC_ABI_LIBRARY", "OFF"},
 			{"LIBCXX_HAS_MUSL_LIBC", "ON"},
 			{"LIBCXX_HARDENING_MODE", "fast"},
+			{"LIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY", "ON"},
 			{"LIBCXXABI_USE_LLVM_UNWINDER", "ON"},
-			{"LIBCXXABI_ENABLE_STATIC_UNWINDER", "OFF"},
+			{"LIBCXXABI_ENABLE_STATIC_UNWINDER", "ON"},
 			{"LIBCXXABI_USE_COMPILER_RT", "ON"},
+			{"LIBCXXABI_STATICALLY_LINK_UNWINDER_IN_STATIC_LIBRARY", "ON"},
 			{"LLVM_INSTALL_BINUTILS_SYMLINKS", "ON"},
 			{"LLVM_INSTALL_UTILS", "ON"},
 			{"LLVM_BUILD_LLVM_DYLIB", "ON"},
@@ -196,6 +198,7 @@ ln -s ld.lld /work/system/bin/ld
 ln -s clang /work/system/bin/cc
 ln -s clang /work/system/bin/cpp
 ln -s clang++ /work/system/bin/c++
+echo '-static-libstdc++' > /work/system/bin/clang++.cfg
 `,
 
 			// LLVM_LINK_LLVM_DYLIB causes llvm test suite to leak system