Overriding TOOLS with 'adb' as the only entry, or with 'adb' as the
final entry in the list fails to match the grep pattern. The current
pattern includes trailing whitespace, likely to distinguish it from
'adbd'. However since `${TOOLS}` is then passed to grep unquoted, any
trailing whitespace would be dropped by the shell.

Fixed by replacing the trailing whitespace with '\>' to mark the end of
the word, which continues to ensure we don't match against 'adbd'.

Signed-off-by: Ben Brown <ben.brown@codethink.co.uk>
Signed-off-by: Khem Raj <raj.khem@gmail.com>