Prior to this commit both daemon/commands.c and spawn/spawn.c used to
include database/engine/rrdenginelib.h, ie. a header file that is available
only when enabling the dbengine feature.
Currently, we add the repository's top-level dir in the compiler's
header search path. This means that code in every top-level directory
within the repo can include headers sibling top-level directories.
This patch makes header inclusion consistent when it comes to files
that are included from sibling top-level directories within the repo.
Before:
```
struct foobar {
avl avl;
...
}
```
After:
```
struct foobar {
avl_t avl;
...
};
```
Which makes figuring out the type from field name easier.
* Add support for spawning processes without pipes.
* Port health_alarm_execute() from mypopen() to netdata_spawn()
* Make alarm notifications asynchronous within a single health thread iteration
* Initial version of spawn server.
* preliminary integration of spawn client with health
