test: fix has() test failure (#37480)

Problem: has("terminfo") test fails on local runs because it expects
"HAVE_UNIBILIUM " in the :version info to mean that nvim was built
without unibilium.

Solution: Assume nvim is built with unibilium if HAVE_UNIBILIUM is
present in the version string and is NOT followed by 0, false, or off.

This isn't affecting CI runs because when the test detects that it is
running in CI it doesn't use the :version string at all.

Resolves https://github.com/neovim/neovim/issues/37456

test/functional/vimscript/has_spec.lua

@@ -67,11 +67,17 @@ describe('has()', function()
   it('"terminfo"', function()
     -- Looks like "HAVE_UNIBILIUM ", "HAVE_UNIBILIUM=1", "HAVE_UNIBILIUM off", ….
     -- Capture group returns the "1"/"off"/….
-    local build_flag =
-      vim.trim((n.exec_capture('verbose version'):match('HAVE_UNIBILIUM([^-]+)') or ''):lower())
+    local build_flag = vim.trim(
+      (n.exec_capture('verbose version'):match('HAVE_UNIBILIUM([^-]+)') or 'missing'):lower()
+    )
     -- XXX: the match() above fails in CI so currently we assume CI always builds with unibilium.
     local is_enabled = t.is_ci()
-      or not (build_flag == '' or build_flag == 'false' or build_flag == '0' or build_flag == 'off')
+      or not (
+        build_flag == 'missing'
+        or build_flag == 'false'
+        or build_flag == '0'
+        or build_flag == 'off'
+      )
     eq(is_enabled and 1 or 0, fn.has('terminfo'))
   end)