e476188c6f
Before this change an invalid licence= in an APKBUILD will pass `abuild
sanitycheck`. '/usr/share/spdx/license.lst' contains one licence per line.
`grep -x` will match partial lines whereas `grep -w` will only match whole
lines.
An simple demonstration is with 'GPL-3.0' which is not a valid SPDX licence
identifier. 'GPL-3.0-only' and 'GPL-3.0-or-later' are valid licences.
```
$ grep --help
BusyBox v1.30.1 (2019-04-26 06:26:16 UTC) multi-call binary.
Usage: grep [-HhnlLoqvsriwFE] [-m N] [-A/B/C N] PATTERN/-e PATTERN.../-f FILE [FILE]...
Search for PATTERN in FILEs (or stdin)
✂
-w Match whole words only
-x Match whole lines only
✂
$ grep -w -F GPL-3.0 /usr/share/spdx/license.lst
GPL-3.0-only
GPL-3.0-or-later
$ grep -x -F GPL-3.0 /usr/share/spdx/license.lst
$
```