tests: abmon-align: avoid test failure

* tests/ls/abmon-align: Don't remove (1d;) the first line of output.
That was making the test consider only 11 of 12 month names.
Rewrite not to use \(.*\), as that provoked a malfunction in GNU sed
on powerpc Mac OS X (though we don't know yet whether this is due to a
sed bug, or to miscompilation).  Nelson Beebe reported the test failure.

tests/ls/abmon-align

@@ -34,9 +34,12 @@ fail=0
 
 for format in "%b" "[%b" "%b]" "[%b]"; do
   for LOC in C gv_GB ga_IE fi_FI.utf8 zh_CN ar_SY $LOCALE_FR_UTF8; do
+    # The sed usage here is slightly different from the original,
+    # removing the \(.*\), to avoid triggering misbehavior in at least
+    # GNU sed 4.2 (possibly miscompiled) on Mac OS X (Darwin 9.8.0).
     n_widths=$(
       LC_ALL=$LOC TIME_STYLE=+"$format" ls -lgG *.ts |
-      LC_ALL=C sed '1d; s/.\{15\}\(.*\) ...ts$/\1/; s/ /./g' |
+      LC_ALL=C sed 's/.\{15\}//;s/ ..\.ts$//;s/ /./g' |
       while read mon; do echo "$mon" | LC_ALL=$LOC wc -L; done |
       uniq | wc -l
     )