Fix errors on shellcheck

Fixes fontconfig/fontconfig#235
3 jobs for issue/235 in 6 minutes and 8 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #2248433
mingw-build

00:05:13

passed #2248431
shared-build

00:06:08

passed #2248432
static-build

00:04:37