patch 9.0.1931: make test_compilers fails on ubuntu

patch 9.0.1931: make test_compilers fails on ubuntu

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: #13173

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Dominique Pellé <dominique.pelle@tomtom.com>