don't run the clean target when building all as we run into parallel races:
- memtest kicks off building of a bunch of .o files
- clean runs in parallel which runs `rm` and deletes some of the new .o
- memtest goes to link and fails because objects are missing

--- a/Makefile
+++ b/Makefile
@@ -19,7 +19,7 @@
       smp.o vmem.o random.o
-all: clean memtest.bin memtest 
+all: memtest.bin memtest
 # Link it statically once so I know I don't have undefined
 # symbols and then link it dynamically so I have full