-fmudflapth on head

[Frank Ch. Eigler]

> I find that on head one has to explicitly give
> 	-lmudflapth -lpthread
> while on tree-ssa branch this was already implied by
> 	-fmudflapth
> [...]
> Is this intentional?

Yes.  The reason is that the gcc.c specs mechanism did not make it
straightforward to pass any dependencies of -lmudflap* into the
constructed linker command line at the ideal spot.  This can happen
for example during static linkage with -lmudflap* with odd
dependencies like -ldl.  libmudflap / dependencies would sometimes
show up too early or too late (after -lc, or before the user objects, IIRC).

- FChE