Problem: make test_compilers fails on ubuntu
Solution: set LC_ALL=C
fix: make test_compiler failed on xubuntu 22.04.3
Problem: 'make test_compiler' failed on Linux xubuntu 22.04.3 but
succeeded on e.g. macOS. To reproduce:
```
$ ./configure --with-features=huge --enable-gui=no --enable-perlinterp=yes
$ make -j12
$ cd vim/src/testdir
$ make test_compiler
...snip...
Found errors in Test_compiler():
command line..script /home/dope/sb/vim/src/testdir/runtest.vim[601]..function RunTheTest[54]..Test_compiler line 24: command did not fail: clist
command line..script /home/dope/sb/vim/src/testdir/runtest.vim[601]..function RunTheTest[54]..Test_compiler line 30: Pattern '\\n \\d\\+ Xfoo.pl:3: Global symbol "$foo" requires explicit package name' does not match '\n19 Xfoo.pl:3: Global symbol "$foo" requires explicit package name (did you forget to declare "my $foo"?)'
make: *** [Makefile:70: test_compiler] Error 1
```
Solution: set `LC_ALL` to "C" in `Test_compiler()`
closes: vim/vim#13173ca0ffc0d63
Co-authored-by: Dominique Pellé <dominique.pelle@tomtom.com>
Problem: There is no way to get a list of swap file names.
Solution: Add the swapfilelist() function. Use it in the test script to
clean up. Remove deleting individual swap files.
c216a7a21a
vim-patch:9.0.1005: a failed test may leave a swap file behind
Problem: A failed test may leave a swap file behind.
Solution: Delete the swap file to avoid another test to fail. Use another
file name.
d0f8d39d20
Cherry-pick test_window_cmd.vim changes from patch 8.2.1593.
Remove FUNC_ATTR_UNUSED from eval functions as fptr is always unused.
Co-authored-by: Bram Moolenaar <Bram@vim.org>
