Fix grep pattern in makealias to work on non-Gnu grep (bug 8368).

Fix grep pattern in makealias to work on non-Gnu grep (bug 8368).

grep -l -w '^foo' doesn't work on Solaris. Replace with
grep -l '^foo\>' instead which does. Also, grep -l will
report the filename more than once (!), so add | head -1
to pick just the first one.