[bug #17873] .NOTPARALLEL enhancements

Follow-up Comment #43, bug #17873 (project make): Another scenario wherein sequential processing of dependencies is useful: all: subdirs $(TARGETS) subdirs: (cd dir1 && make) (cd dir2 && make) and the $(TARGETS) depend upon libraries (.a files) that are made by dir1 and/or dir2.

[bug #36542] make -j interacts badly with pattern rules, .SECONDARY:

has been built. 5. Comment out the ".SECONDARY:" line in the Makefile. 6. Do "make clean". 7. Do "make -j 20". Notice that the make succeeds (but it deletes all of the .c and .o files because the