posix: define M_PI and other stuff in Zephyr sketches #743

Job	Run time
Build and package cores	8m 58s
Split off zephyr_main	12s
Split off zephyr_contrib	7s
Split off zephyr	9s
Split off zephyr_unoq	6s
Test zephyr_main:nano33ble	2m 33s
Test zephyr_main:opta	2m 28s
Test zephyr_main:portentac33	2m 34s
Test zephyr_contrib:ek_ra8d1	2m 26s
Test zephyr_main:giga	2m 27s
Test zephyr_main:niclasense	2m 28s
Test zephyr:unoq	2m 23s
Test zephyr_contrib:frdm_mcxn947	2m 25s
Test zephyr_main:portentah7	2m 33s
Test zephyr_contrib:frdm_rw612	2m 30s
Collect logs	6s
Publish jsons	23s
Publish core	0s
verify-core	0s
cleanup-artifacts	4s
	34m 52s

Provide feedback