a68354ebc5
Changes:
* argument sanity checks:
* `PKGNAME[-PKGVER] | SRCURL`
* check if missing
* check if specified more than once (see below)
* specifying more than one buildtype flag
* `-n` (set pkgname) without using SRCURL as last argument
* `-s` (sourceforge source) without using PKGNAME as last argument
* Typo fix: exist -> exists
* `usage()`:
* always print PKGNAME and PKGDESC (instead of NAME and DESC,
NAME was used in one place and PKGNAME in another)
* link to <https://spdx.org/licenses/>
* `-m` (meson) flag was missing in short usage line at the top
* indicate that the buildtypes are exclusive
* `-c` flag: remove "to new directory" wording to make the
message shorter (this should be obvious)
* remove empty line at the end
NOTE: Before this commit, the `PKGNAME[-PKGVER] | SRCURL` was allowed
to be specified more than once, and the code looped over the arguments.
But this was not documented in `usage()` and had unexpected results:
```
$ newapkbuild first second third
$ tree
.
___ first
___ APKBUILD
___ first
___ ___ APKBUILD
___ ___ first
___ ___ ___ APKBUILD
___ ___ ___ src
___ ___ src
___ src
```