Ignore the various (MY)META.(json|yaml) files
Add missing build requirements
Avoid undefined variable warning
Fix test failure when NYTProf (and hence flamegraph) is not installed

Since flamegraph is only necessary when actually generating the flame graph,
allow aggregation to proceed and only die when creating the flame graph.
Work around a 5.14 (and maybe 5.16) parsing oddity

The __LINE__ token in the BEGIN block gets expanded to the last line of the
heredoc rather than the first as it is in 5.18.
Add basic tests for programs embedding Perl
Fix exception handling code to work in embedded Perl interpreters

It turns out the XCPT_ macros described in perlguts ony work if the code
potentially croak()ing is not a runloop call; for that case we need the full
handling code (taken from S_docatch in pp_ctl.c).

This fixes C programs embedding Perl, calling call_sv() from the top level
without the G_EVAL (tests added in the previous commit).
Don't crash on COPs with NULL CopFILE
Allow sampling intervals greater or equal than one second