Log Message:
clang: update to 10.0.0nb4.

Make perl a run-time dependency to fix

ERROR: [check-interpreter.mk] The interpreter "/usr/pkg/bin/perl" of \ 
"/usr/pkg/bin/scan-build" does not exist.
ERROR: [check-interpreter.mk] The interpreter "/usr/pkg/bin/perl" of \ 
"/usr/pkg/libexec/c++-analyzer" does not exist.
ERROR: [check-interpreter.mk] The interpreter "/usr/pkg/bin/perl" of \ 
"/usr/pkg/libexec/ccc-analyzer" does not exist.