When agent is not recording, Observer API fcall_init callback shouldn't
do anything, including framework detection. This is how the agent
operated before it used Observer API to hook into Zend Engine.

…handlers (#1113)

Our instrumentation of framework exception handlers can result in
excess, unwanted error events being generated. Sometimes, these events
are plentiful and diverse enough that manual filtering through them with
our other error related INI options is too much effort. In cases like
that, this setting exists as an easy solution. Errors may still appear
on spans, but error events will, in general, not be created. This works
especially well when the customer inserts their own error handling logic
into the stack, so that they are able to call our API for certain,
specific errors that they wish to be error events.

#1104)

This implements the sampling spec to allow control over the agent
sampling decisions based on the value in the sampled flag of an inbound
traceparent header.

---------

Co-authored-by: Michal Nowacki <[email protected]>

…on(true) (#1072)

Some transaction globals were leaked when calling
`newrelic_end_transaction(true)`. The freeing of these transaction
globals has been moved to join all the other transaction globals to
alleviate this.

In so doing, additional rshutdown methods are needed. This is because
the transaction globals contain reference incremented zvals. If we wait
until postdeactivate, those zvals will be in an undefined state and the
data structures containing those references cannot be properly freed. In
line with other transaction globals, we trigger a shutdown method during
rshutdown to free these globals while the zvals are still valid.

Co-authored-by: Michal Nowacki <[email protected]> who added go version check and go autoupdate.