minor, use trampoline and ucontext functions for slju coroutines

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
chore, adapt truck.c to new mandatory free_coru() as counterpiece to make_coru()

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
hygiene, use TMP() symbol generator for make_coru() symbols

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
fix, PEBKAC, pass in arguments for next() directly (no static buffer in between)

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, provide macro to detect whether asm backed coroutines would work

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, check for asm backed corus during configure and use them if available

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
Merge branch 'core/coru-slju'

* core/coru-slju:
  minor, check for asm backed corus during configure and use them if available
  minor, provide macro to detect whether asm backed coroutines would work
  fix, PEBKAC, pass in arguments for next() directly (no static buffer in between)
  hygiene, use TMP() symbol generator for make_coru() symbols
  chore, adapt truck.c to new mandatory free_coru() as counterpiece to make_coru()
  minor, use trampoline and ucontext functions for slju coroutines