Quote marks are not special to make: as it can't find
external/"x86_64-linux-gnu"/libwally-core-build/src/libwallycore.la
it always insists on rebuilding it (which rebuilds the world).
If we have spaces in TARGET_DIR, we're in trouble already.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-None
57f6f74ee0