Pass full path to /usr/include/dtrace.h to work around ruby's header
Pass full path to /usr/include/dtrace.h to work around ruby's header

The Ruby runtime probes supply a dtrace.h in the ruby include directory,
which ends up being ahead of /usr/include in the search path, and we fail
to add -ldtrace to the linked libraries.

chrisa/ruby-dtrace,chrisa/ruby-dtrace