build: Avoid detecting bogus components named 'x'

The function find_things() in configure is confused by component
registration calls as part of multiline macros defining combined
component registration.  Coalesce those macros into one line to
work around the issue.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
Signed-off-by: Martin Storsjö <martin@martin.st>