vim-patch:8.2.2587: recover test fails on FreeBSD

Problem:    Recover test fails on FreeBSD.
Solution:   Check for Linux.

6635ae1437

Co-authored-by: Bram Moolenaar <Bram@vim.org>

src/nvim/testdir/check.vim

@@ -90,6 +90,14 @@ func CheckUnix()
   endif
 endfunc
 
+" Command to check for running on Linux
+command CheckLinux call CheckLinux()
+func CheckLinux()
+  if !has('linux')
+    throw 'Skipped: only works on Linux'
+  endif
+endfunc
+
 " Command to check that making screendumps is supported.
 " Caller must source screendump.vim
 command CheckScreendump call CheckScreendump()

src/nvim/testdir/test_recover.vim

@@ -82,8 +82,9 @@ func Test_swap_file()
 endfunc
 
 func Test_nocatch_process_still_running()
-  " assume Unix means sysinfo.uptime can be used
-  CheckUnix
+  " sysinfo.uptime probably only works on Linux
+  CheckLinux
+  " the GUI dialog can't be handled
   CheckNotGui
 
   " don't intercept existing swap file here