Source lang-default rather than open-coding

the setting/exporting of LANG, LC_ALL, and LANGUAGE.

tests/ls/symlink-slash

@@ -20,8 +20,7 @@ if test $framework_failure = 1; then
   exit 1
 fi
 
-LANGUAGE=C; export LANGUAGE
-LANG=C; export LANG
+. $srcdir/../lang-default
 
 fail=0
 set `ls -l symlink/`

tests/ls/time-1

@@ -46,8 +46,7 @@ ln c d || framework_failure=1
 # Date output in ls -l is locale-sensitive, so this test fails if the
 # current locale produces a date that doesn't match the embedded value
 # here (Jan 15 23:00:00 1998), which is in the C (POSIX) locale.
-LC_ALL=C
-export LC_ALL
+. $srcdir/../lang-default
 
 # Before we go any further, verify that touch's -m option works.
 set -- `ls --full -l a`