Building --with-dtrace requires objdump from GNU binutils. This change inserts a helpful error message if there is a problem executing objdump.
genv8constants was much slower than necessary due to lack of pipe buffering.
* fixes #2110 * includes V8 postmortem metadata in Solaris builds * adds GYP support for DTrace probes and ustack helper * ustack helper derives constants dynamically from libv8_base.a * build with DTrace support by default on SunOS
