meson: add build target feedback to summary #1907

Job	Run time
build-linux (ubuntu-20.04, focal, clang-15, 12.2.Rel1)	3m 34s
build-mingw (windows-2022, ucrt64)	2m 26s
build-linux (focal, 96b_carbon	42s
build-linux (ubuntu-20.04, focal, gcc-11, 12.2.Rel1)	3m 41s
size-diff	47s
build-mingw (windows-2022, clang64)	2m 18s
build-linux (focal, bluepill	33s
build-linux (focal, f072	33s
build-linux (focal, f3	39s
build-linux (focal, f4discovery	35s
build-linux (focal, hydrabus	39s
build-linux (focal, launchpad-icdi	33s
build-linux (focal, native	35s
build-linux (focal, stlink	39s
build-linux (focal, stlinkv3	34s
build-linux (focal, swlink	32s
	19m 20s

Provide feedback