llext: fix alignment of cold / detached sections #20102

Job	Run time
build-linux (mnfst, imx8 imx8x imx8m imx8ulp)	6m 30s
build-windows (imx8 imx8x imx8m imx8ulp)	8m 0s
build-linux (mnfst, mtl lnl)	6m 1s
build-windows (mtl lnl)	7m 27s
build-linux (mnfst, ptl)	4m 29s
build-windows (ptl)	6m 24s
build-linux (mnfst, tgl tgl-h)	5m 23s
build-windows (tgl tgl-h)	8m 30s
build-linux (zmain, imx8 imx8x imx8m imx8ulp)	6m 23s
build-linux (zmain, mtl lnl)	5m 40s
build-windows (-d, lnl)	5m 44s
build-linux (zmain, ptl)	4m 30s
build-linux (zmain, tgl tgl-h)	5m 26s
manifest-check	49s
LP64-WIP	3m 59s
build-linux (-d, mnfst, lnl)	4m 40s
build-linux (mnfst, --all)	13m 54s
compare-linux-win	28s
	1h 44m 17s

Provide feedback