freetype: clean before building for buildbot builds
On macOS, when reconfiguring with a new location, the library does not get relinked with a new library ID; force a clean build to make sure it is updated properly.
Cc: @chuck.atkins
On macOS, when reconfiguring with a new location, the library does not get relinked with a new library ID; force a clean build to make sure it is updated properly.
Cc: @chuck.atkins