media-libs/lsp-plugins: tests require USE=jack

Interestingly enough, only JACK is required here - src_test() runs fine
with USE="-ladspa -lv2" (and the relevant dependencies removed, to be
sure).

Path-of-least-resistance fix following having observed this problem
while debugging an unrelated issue, perhaps with a bit of effort one
could either isolate JACK dependency to only affect the test phase or
make it optional.

Closes: https://bugs.gentoo.org/768798
Signed-off-by: Marek Szuba <[email protected]>

media-libs/lsp-plugins/lsp-plugins-1.1.29.ebuild

@@ -20,8 +20,11 @@ fi
 
 LICENSE="LGPL-3"
 SLOT="0"
-IUSE="doc jack ladspa +lv2"
-REQUIRED_USE="|| ( jack ladspa lv2 )"
+IUSE="doc jack ladspa +lv2 test"
+REQUIRED_USE="|| ( jack ladspa lv2 )
+ test? ( jack )"
+
+RESTRICT="!test? ( test )"
 
 DEPEND="
  dev-libs/expat