Commit a21163aed (package/blktrace: do not build in parallel) tried to fix
the parallel build issue, but the package doesn't use the autotools package
infrastructure so BLKTRACE_MAKE isn't used. Instead replace the explicit
$(MAKE) calls with $(MAKE1).
Cc: "Yann E. MORIN" <yann.morin.1998@free.fr> Signed-off-by: Peter Korsgaard <peter@korsgaard.com>