clang/llvm build failure

[bch <brad.harder%gmail.com@localhost>]

[...]
x86_64--netbsd-gcc: error:
/usr/src/external/bsd/llvm/lib/libLLVMSupport/../../dist/llvm/lib/Support/ConvertUTF.c:
No such file or directory
x86_64--netbsd-gcc: fatal error: no input files
compilation terminated.
nbmkdep: compile failed.
[...]