main/mariadb: quote variables

Partial fix. Subsequent scripts like 'mysqld_safe' still do not handle whitespaces in filenames properly.
7 jobs for !14809 with initd-getconf-fix in 1 minute and 19 seconds (queued for 1 second)
detached
Status Job ID Name Coverage
  Lint
passed #251286
x86_64 docker-alpine
lint

00:00:22

 
  Build
passed #251291
aarch64 ci-build docker-alpine
build-aarch64

00:00:33

passed #251292
armv7 ci-build docker-alpine
build-armv7

00:00:42

passed #251290
ppc64le ci-build docker-alpine
build-ppc64le

00:00:54

passed #251289
s390x ci-build docker-alpine
build-s390x

00:00:51

passed #251288
x86 ci-build docker-alpine
build-x86

00:00:27

passed #251287
x86_64 ci-build docker-alpine
build-x86_64

00:00:29