[Proj] pj_malloc() inits P->es as junk memory

[David Turover]

I had semi-random failures in my modified pj_goode (which uses pj_gn_sinu
and pj_moll) where the results from sinu would come back as inf, inf. In
these cases, sinu was initialized to use its ellipsoid functions instead
of its spherical functions.

It seems P->es was not initialized in PJ_gn_sinu.c ENTRY1(sinu, en) where
P->es is checked to see whether the spherical or ellipsoid functions should
be used. Every so often, malloc would put memory with nonzero data in P->es.

This can be fixed by replacing malloc() with calloc() at pj_alloc.c line 20: 

	// void *res = malloc(size);
	void *res = (void*) calloc(size, sizeof(void));


The random inf problem should happen with the official pj_goode as well.
I haven't tested it, but I didn't modify it enough that it should matter
to this issue.

Note: pj_gn_sinu's setup() sets P->es to zero, but that function is not
called until after P->es is first tested in ENTRY1. It can't be moved
before the test because that would wipe out any intentional setting of
P->es to a nonzero value from an outside function that calls ENTRY1 on an
already allocated sinu object.

 - David T.