arm: Move the sub_sp and sub_sp_aligned macros to the shared util file

The arm32 version is less generic and has a bit more caveats, but still
belongs as a shared utility in a header.
35 jobs for arm-subsp in 6 minutes and 10 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Style
passed #543140
amd64 docker
style-check

00:00:06

passed #543141
amd64 docker
x86inc-check

00:00:06

 
  Build
passed #543153
amd64 docker
build-android-aarch64

00:00:11

passed #543152
amd64 docker
build-android-armv7

00:00:11

passed #543142
amd64 avx2 docker
build-debian

00:00:24

passed #543154
aarch64 docker
build-debian-aarch64

00:00:25

passed #543155
aarch64 docker
build-debian-aarch64-clang-5

00:00:12

passed #543158
armv7 docker
build-debian-armv7

00:00:45

passed #543159
armv7 docker
build-debian-armv7-clang-5

00:00:36

passed #543145
amd64 docker
build-debian-examples

00:00:22

passed #543146
amd64 docker
build-debian-no-tools

00:00:18

passed #543161
ppc64le docker
build-debian-ppc64le

00:02:28

passed #543143
amd64 docker
build-debian-static

00:00:23

passed #543157
aarch64 docker
build-debian-werror

00:00:21

passed #543144
amd64 docker
build-debian32

00:00:26

passed #543156
catalina amd64
build-macos

00:00:39

passed #543162
amd64 docker
build-pages

00:00:10

passed #543160
amd64 docker
build-ubuntu-snap

00:00:26

passed #543150
amd64 docker
build-win-arm32

00:00:11

passed #543151
amd64 docker
build-win-arm64

00:00:14

passed #543147
amd64 docker
build-win32

00:00:37

passed #543148
amd64 docker
build-win32-unaligned-stack

00:00:31

passed #543149
amd64 docker
build-win64

00:00:41

 
  Test
passed #543163
amd64 docker
test-debian

00:01:11

95.8364%
passed #543172
aarch64 docker
test-debian-aarch64

00:00:26

passed #543174
armv7 docker
test-debian-armv7-clang-5

00:01:11

passed #543167
amd64 docker
test-debian-asan

00:02:58

passed #543164
avx2 amd64 docker
test-debian-asm

00:00:57

passed #543168
amd64 docker
test-debian-msan

00:00:59

passed #543173
ppc64le docker
test-debian-ppc64le

00:03:20

passed #543170
amd64 docker
test-debian-tsan

00:04:27

passed #543169
amd64 docker
test-debian-ubsan

00:02:27

passed #543166
amd64 avx2 docker
test-debian-unaligned-stack

00:00:47

passed #543165
avx2 amd64 docker
test-debian32-asm

00:01:00

passed #543171
amd64 avx2 docker
test-win64

00:01:04