The variable inheritance system can leave extra spaces in a variable
when multiple levels of inheritance are used. It can expand:
"@inherit:foo @inherit:bar @inherit:baz"
to
"value @inherit:bar @inherit:baz"
and then
"value @inherit:baz" (if bar has no value for the variable)
and then
"value " (if baz also has no value).
Call strip to remove excess spaces between words after each
replacement pass.
Change-Id: Ic4cfc6fed1865066a6353a522e4bdcb68ec875d3
