Make 3.81 and 3.82 break on parallel build

[david . hagood]

I have a make file that includes a set of machine generated dependency
files. Those files describe a set of shared libraries to be build, of the
form:

somedir/libfoo.so: somedir/libbar.so somedir/libbaz.so

Note that "libfoo.so" has explicitly stated it depends upon
somedir/libbar.so.

libbar.so has a similar dependency file that describes its needs:

somedir/libbar.so: somedir/libbaz.so otherdir/bar.o

My make file then is commanded to build the various files:

.PHONEY: mytarget
mytarget: somedir/libfoo.so somedir/libbar.so somedir/libbaz.so

If I run a plain make:
  make mytarget

all is well: Make correctly builds otherdir/bar.o, somedir/libbaz.so,
somedir/libbar.so, then finally somedir/libfoo.so, in that order.

However, if I run a parallel make:
  make -j4 mytarget

then make will happly start building everything, and will try to link
somedir/libfoo.so before even STARTING on linking somedir/libbar.so.

Again: all the dependencies are fully described: there's no reason make
shouldn't see that it has to wait before building somedir/libfoo.so.