[PATCH 3/4] meson: require Perl when building docs

[Patrick Steinhardt <ps@pks.im>]

From: Eli Schwartz <eschwartz@gentoo.org>

When building our documentation we require Perl to generate the list of
commands via "cmd-list.perl". Having a Perl interpreter available is
thus mandatory when building documentation, but Meson does not enforce
this prerequisite. Thus, when all optional features that depend on Perl
are disabled, we won't look up the Perl interpreter, which will in the
end lead to an error at setup time:

```
$ meson setup builddir/ -Ddocs=man -Dperl=disabled -Dtests=false
[...]
Documentation/meson.build:308:22: ERROR: Tried to use not-found external program in "command"
```

There is already a list of other cases where we do need the Perl
interpreter. Building documentation should be one of those cases, but
is missing from the list. Add it to fix the issue.

Signed-off-by: Eli Schwartz <eschwartz@gentoo.org>
Commit-message-edited-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/meson.build b/meson.build
index a8d1e63ccc6..51013c70de9 100644
--- a/meson.build
+++ b/meson.build
@@ -772,7 +772,7 @@ endif
 # features. It is optional if you want to neither execute tests nor use any of
 # these optional features.
 perl_required = get_option('perl')
-if get_option('tests') or get_option('gitweb').enabled() or 'netrc' in get_option('credential_helpers')
+if get_option('tests') or get_option('gitweb').enabled() or 'netrc' in get_option('credential_helpers') or get_options('docs') != []
   perl_required = true
 endif
 

-- 
2.49.0.472.ge94155a9ec.dirty